How is the Internet different from the World Wide Web? What is the World Wide Web and who invented it? World Wide Web examples

World Wide Web (abbreviated world wide web or WWW) is a unity of information resources that are interconnected by means of telecommunications and are based on a hypertext representation of data scattered around the world.

1989 is considered to be the birth year of the World Wide Web. It was in this year that Tim Berners-Lee proposed a general hypertext project, which later became known as the World Wide Web.

The creator of the "web" Tim Bernes-Lee, working in the particle physics laboratory of the European Center for Nuclear Research "CERN" in Geneva (Switzerland), together with partner Robert Cailliaud, dealt with the problems of applying the ideas of hypertext to build an information environment that would simplify the exchange of information between physicists .

The result of this work was a document that discussed concepts that are of fundamental importance for the "web" in its modern form, and proposed URIs, the HTTP protocol, and the HTML language. Without these technologies, it is no longer possible to imagine the modern Internet.

Berners-Lee created the world's first web server and the world's first hypertext web browser. On the world's first website, he described what the World Wide Web is and how to set up a web server, how to use a browser, and so on. This site was also the world's first Internet catalog.

Since 1994, the most important tasks for the development of the World Wide Web have been taken over by the World Wide Web Consortium ( World Wide Web Consortium, W3C), which was organized and still headed by Kim Bernes-Lee. The consortium develops and implements technological standards for the Internet and the World Wide Web. Mission of the W3C: "Unleash the full potential of the World Wide Web by creating protocols and principles that guarantee the long-term development of the Web." W3C develops "Recommendations" to achieve compatibility between software products and hardware of different companies, which makes the World Wide Web more perfect, versatile and convenient.

Search engines: composition, functions, principles of work.

Search system - this is a software and hardware complex designed to search the Internet and respond to a user request, specified in the form of a text phrase (search query), by issuing a list of links to information sources, in order of relevance (in accordance with the request). The largest international search engines: Google, "Yahoo", "MSN". On the Russian Internet, this is "Yandex", Rambler, "Aport".

Let's describe main characteristics of search engines :

completeness

Completeness is one of the main characteristics of a search engine, which is the ratio of the number of documents found by request to the total number of documents on the Internet that satisfy this request. For example, if there are 100 pages on the Internet containing the phrase “how to choose a car”, and only 60 of them were found for the corresponding query, then the search recall will be 0.6. Obviously, the more complete the search, the less likely it is that the user will not find the document he needs, provided that it exists on the Internet at all.

Accuracy

Accuracy is another main characteristic of a search engine, which is determined by the degree to which the found documents match the user's query. For example, if the query “how to choose a car” contains 100 documents, 50 of them contain the phrase “how to choose a car”, and the rest simply contain these words (“how to choose the right radio and install it in a car”), then the search accuracy is considered equal to 50/100 (=0.5). The more accurate the search, the faster the user will find the documents he needs, the less various kinds of “garbage” will be found among them, the less often the documents found will not match the request.

Relevance

Relevance is an equally important component of the search, which is characterized by the time that passes from the moment documents are published on the Internet until they are entered into the index database of the search engine. For example, the day after the appearance of interesting news, a large number of users turned to search engines with relevant queries. Objectively, less than a day has passed since the publication of news information on this topic, however, the main documents have already been indexed and searchable, thanks to the existence of the so-called “fast base” of large search engines, which is updated several times a day.

Search speed

Search speed is closely related to its load tolerance. For example, according to OOO Rambler Internet Holding, today about 60 requests per second come to the Rambler search engine during business hours. Such a workload requires a reduction in the processing time of a single request. Here, the interests of the user and the search engine coincide: the visitor wants to get results as quickly as possible, and the search engine must process the request as quickly as possible so as not to slow down the calculation of the next requests.

visibility

The visibility of the presentation of results is an important component of a convenient search. For most queries, the search engine finds hundreds or even thousands of documents. Due to the lack of clarity in the formulation of queries or the inaccuracy of the search, even the first pages of the issuance do not always contain only the necessary information. This means that the user often has to make his own search within the found list. Various elements of the search engine results page help you navigate the search results. Detailed explanations on the search results page, for example, from Yandex, can be viewed at the link http://help.yandex.ru/search/?id=481937.

A Brief History of the Development of Search Engines

In the initial period of the development of the Internet, the number of its users was small, and the amount of available information is relatively small. For the most part, only research workers had access to the Internet. At that time, the task of searching for information on the Internet was not as relevant as it is now.

One of the first ways to organize access to information resources of the network was the creation of open catalogs of sites, links to resources in which were grouped according to the subject. The first such project was Yahoo.com, which opened in the spring of 1994. After the number of sites in the Yahoo directory increased significantly, the ability to search for the necessary information in the directory was added. In the full sense, it was not yet a search engine, since the search scope was limited to only the resources present in the directory, and not to all Internet resources.

Link directories were widely used in the past, but have almost completely lost their popularity at the present time. Since even modern, huge catalogs contain information about only a negligible part of the Internet. The largest network directory DMOZ (also called the Open Directory Project) contains information about 5 million resources, while the Google search engine database consists of more than 8 billion documents.

The first full-fledged search engine was the WebCrawler project, which was published in 1994.

In 1995, the search engines Lycos and AltaVista appeared. The latter has been a leader in the field of information search on the Internet for many years.

In 1997, Sergey Brin and Larry Page created the Google search engine as part of a research project at Stanford University. Google is currently the most popular search engine in the world!

In September 1997, the Yandex search engine, which is the most popular on the Russian-speaking Internet, was officially announced.

Currently, there are three major international search engines - Google, Yahoo and MSN, which have their own databases and search algorithms. Most other search engines (of which there are a large number) use the results of the three listed in one form or another. For example, AOL search (search.aol.com) uses Google, while AltaVista, Lycos, and AllTheWeb uses Yahoo.

The composition and principles of the search engine

In Russia, the main search engine is Yandex, further - Rambler.ru, Google.ru, Aport.ru, Mail.ru. Moreover, at the moment, Mail.ru uses the Yandex search engine and database.

Almost all major search engines have their own structure, different from others. However, it is possible to single out the main components common to all search engines. Differences in the structure can only be in the form of implementation of the mechanisms of interaction of these components.

Indexing module

The indexing module consists of three auxiliary programs (robots):

Spider (spider) is a program for downloading web pages. The "spider" downloads the page and extracts all internal links from this page. The html code of each page is downloaded. Robots use HTTP protocols to download pages. The "spider" works as follows. The robot sends the “get/path/document” request and some other HTTP request commands to the server. In response, the robot receives a text stream containing service information and the document itself.

Page URL

the date the page was downloaded

server response http header

page body (html code)

Crawler ("traveling" spider) - a program that automatically follows all the links found on the page. Selects all links present on the page. Its task is to determine where the spider should go next, based on links or based on a predefined list of addresses. Crawler, following the found links, searches for new documents that are still unknown search engine.

Indexer (robot indexer) - a program that analyzes web pages downloaded by spiders. The indexer parses the page into its component parts and analyzes them using its own lexical and morphological algorithms. Various elements of the page are analyzed, such as text, headings, links, structural and style features, special service html tags, etc.

Thus, the indexing module makes it possible to traverse a given set of resources by reference, download encountered pages, extract links to new pages from received documents, and perform a complete analysis of these documents.

Database

A database, or search engine index, is a data storage system, an information array that stores specially converted parameters of all documents downloaded and processed by the indexing module.

search server

The search server is the most important element of the entire system, since the quality and speed of the search directly depend on the algorithms that underlie its functioning.

The search server works like this:

The request received from the user is subjected to morphological analysis. An information environment is generated for each document contained in the database (which will subsequently be displayed as a snippet, that is, corresponding to the request of text information on the search results page).

The received data is passed as input parameters to a special ranking module. Data is processed for all documents, as a result of which, for each document, its own rating is calculated, characterizing the relevance of the query entered by the user, and the various components of this document stored in the search engine index.

Depending on the user's choice, this rating can be adjusted by additional conditions (for example, the so-called "advanced search").

Next, a snippet is generated, that is, for each document found, a title, a brief annotation that best matches the request, and a link to the document itself are extracted from the document table, and the found words are highlighted.

The received search results are transmitted to the user in the form of SERP (Search Engine Result Page) - the page for issuing search results.

As you can see, all these components are closely related to each other and work in interaction, forming a clear, rather complex mechanism for the search engine, which requires a huge amount of resources.

No search engine covers all the Internet resources.

Each search engine collects information about Internet resources using its own unique methods and forms its own periodically updated database. Access to this database is granted to the user.

Search engines implement two ways to search for a resource:

Search by topic catalogs - information represented as a hierarchical structure. At the top level there are general categories (“Internet”, “Business”, “Art”, “Education”, etc.), at the next level the categories are divided into sections, etc. The lowest level - links to specific web pages or other information resources.

Keyword search (index search or detailed search) - the user submits to the search engine request, consisting of keywords. System returns to the user a list of resources found upon request.

Most search engines combine both search methods.

Search engines can be local, global, regional and specialized.

In the Russian part of the Internet (Runet), the most popular general-purpose search engines are Rambler (www.rambler.ru), Yandex (www.yandex.ru), Aport (www.aport.ru), Google (www.google.ru).

Most search enginesimplemented in the form of portals.

Portal (from English.portal- main entrance, gate) is a website that integrates various Internet services: search tools, mail, news, dictionaries, etc.

Portals can be specialized (like,www. Museum. en) and general (for example,www. km. en).

Keyword Search

The set of keywords that are searched for is also called the search term or search topic.

A request can consist of either a single word or a combination of words combined with operators - symbols by which the system determines what action it needs to perform. For example: the query “Moscow Peter” contains an AND operator (this is how a space is perceived), which indicates that you need to look for documents that contain both words - both Moscow and Peter.

In order for the search to be relevant (from the English relevant - relevant, relevant), several general rules should be taken into account:

Regardless of the form in which the word is used in the query, the search takes into account all its word forms according to the rules of the Russian language. For example, the query “ticket” will also find the words “ticket”, “ticket”, etc.

Capital letters should only be used in proper names so as not to view unnecessary links. At the request of "blacksmiths", for example, documents will be found that talk about blacksmiths and the Kuznetsovs.

It is advisable to narrow your search by using a few keywords.

If the desired address is not among the first twenty addresses found, you should change the request.

Each search engine uses its own query language. To get acquainted with it, use the built-in help of the search engine.

Large sites may have built-in search engines within their web pages.

Queries in such search engines, as a rule, are built according to the same rules as in global search engines, but familiarity with the help will not be superfluous here either.

Advanced Search

Search engines may provide a mechanism for the user to form a complex query. Following a link Advanced Search allows you to edit search parameters, specify additional parameters and choose the most convenient form of displaying search results. The following describes the parameters that can be specified in an advanced search in the HindEx and Rambler systems.

Some search engines (for example, Yandex) allow you to enter queries in natural language. You write what you need to find (for example: ordering train tickets from Moscow to St. Petersburg). The system analyzes the request and returns the result. If it does not suit you, switch to the query language.

The rapid development of the Internet, which has been taking place over the past 15 years, is primarily due to the emergence of the World Wide Web. "World Wide Web" is a loose translation of the English phrase "World Wide Web", which is often referred to as WWW or Web.

World Wide Web technology. The World Wide Web uses hypertext technology, in which documents are linked together using hyperlinks.

As link pointers Web pages can use text fragments that are highlighted with color and underlining, as well as graphics that are highlighted with a frame. Activating a link pointer on the original Web page (for example, by clicking it) causes a transition to the desired Web page (Fig. 6.10).

The World Wide Web are hundreds of millions of Internet Web servers containing hundreds of billions of Web pages that use hypertext technology.

The web page may be multimedia, that is, it can contain various multimedia objects: graphic images, animation, sound and video.

The web page may be interactive, i.e. contain forms with fields that are used when registering users of free e-mail, when shopping in online stores, etc.

Topically related Web pages are usually presented in the form website, i.e., an integral system of documents interconnected into a single whole with the help of links.

Web page address. There are a huge number of Web pages currently stored on Internet Web servers. You can find a Web page on the Internet using the address of the Web page.

Web page address includes how the document is accessed and the name of the Internet server where the document resides.

The Hyper Text Transfer Protocol (HTTP) is used as a way to access Web pages. When writing a protocol, its name is followed by a colon and two slashes: http://

As an example, let's write down the address of the title page of the Web site "Computer Science and Information Technologies". The page is located on the server iit.metodist.ru, therefore, the address takes the form:

http://iit.methodist.ru

Browsers. Viewing Web pages is carried out with the help of special viewer programs - browsers. Currently the most common browsers are Internet Explorer, Mozilla and Opera.

The browser window (Fig. 6.11) contains the standard elements of the application window:
- window menu containing sets of commands File, Edit, View, Favorite, Service and Reference;
- a toolbar whose buttons allow you to navigate from one Web page to another (buttons Forward, Back, Home), as well as manage the process of loading them (buttons Stop, Refresh);
- text field The address:, in which the Internet address of the desired Web page is entered from the keyboard or selected from the list;
- workspace in which web pages are viewed.

Rice. 6.11. Internet browsers Explorer, Mozilla and Opera

Virtual travel on the World Wide Web. If the computer is connected to the Internet, then you can launch one of the browsers and go on a virtual journey through the World Wide Web. The browser will automatically load the initial web page (the address of the web page from which the journey begins can be changed using the browser settings).

When a Web page is opened in a browser on a user's computer, it makes a long journey from a remote Internet server through information transfer channels through several intermediate Internet servers. The speed of loading a Web page does not depend on the distance to the Web server, but on the number of intermediate servers and the quality of the communication lines through which information is transmitted from server to server. There may be a situation where a Web page loads much faster from a server located on a different continent than from a server located on the next street.

To go to another web page in the text box The address: you must enter its Internet address. Many Web pages contain hyperlinks to other Web pages, so you can continue your journey on the World Wide Web by activating one of them.

In the process of reading a book (textbook, reference book, encyclopedia), it is often necessary to return to the material read. For a faster search for the desired page, so-called "bookmarks" are often inserted into the book. When traveling on the World Wide Web, it is advisable to save Internet addresses of interesting Web pages as "bookmarks" in the browser. To visit such a page, it will be enough to activate one of the "bookmarks".

test questions

1. What is the function of hyperlinks in the technology of the World Wide Web?

2. What parts does a Web page address consist of?

6.5. Short answer question. Record the address of a Web page stored on an Internet server registered in the first-level domain ru, the second-level domain schools and having its own name www.

Email

Electronic mail (e-mail) is the most common Internet service. It is historically the first information service of computer networks and does not require the mandatory availability of high-speed and high-quality communication lines.

E-mail has several significant advantages over regular mail. The most important of these is the speed of message forwarding. If a letter by regular mail can take days or weeks to reach the addressee, then a letter sent by e-mail reduces the transmission time to several tens of seconds or, in the worst case, to several hours.

Another advantage is that an e-mail can contain not only a text message, but also attachments (programs, graphics, sound, etc.). In addition, e-mail allows you to send a message to several subscribers at once, forward letters to other addresses, etc.

E-mail address. In order for an e-mail to reach the addressee, it, in addition to the message itself, must contain the e-mail address of the recipient of the letter.

The first part of the mail address usename is arbitrary and is set by the user when registering the mailbox. The second part server.ru is the name of the Internet mail server on which the user has registered his mailbox.

E-mail address is written in a specific form and consists of two parts, separated by the @ symbol: [email protected]

The e-mail address is written only in Latin letters and should not contain spaces. For example, if the mail server name is metodist.ru, then the user mailbox names will look like this:

[email protected]

Email subscriber addresses are stored on the user's computer in the Address Book database. The address book contains the subscriber's name, e-mail address, phone number and other data (Fig. 6.12).

Rice. 6.12. Database "Address Book"

Functioning of e-mail. An Internet user can register a mailbox on the provider's mail server, which will accumulate transmitted and received e-mails.

The mail program creates a mail message on the local computer. At this stage, in addition to writing the text of the message, you must specify the address of the recipient of the message (you can take it from the "Address Book"), the subject of the message and attach files to the message, if necessary.

The process of sending a message begins with connecting to the Internet and delivering the message to your mailbox on a remote mail server. The mail server will immediately send this message through the Internet mail server system to the recipient's mail server in his mailbox.

To receive a letter, the recipient must connect to the Internet and deliver mail from his mailbox on a remote mail server to his local computer (Figure 6.13).

Mail programs usually also provide the user with numerous additional services for working with mail (selecting addresses from the address book, automatically sending messages to specified addresses, etc.).

Outlook Express mail program. To work with e-mail, special e-mail programs are required. The Outlook Express mail program, which is part of the operating system Windows. After launching Outlook Express, an application window appears, which consists of four parts (Fig. 6.14).

Rice. 6.14. Outlook Express window

In the upper left part of the window there is a list of folders in which emails are stored:
- inbox- contains received letters;
- outgoing- contains sent letters from the moment of creation to the moment of delivery from the user's local computer to the provider's mail server;
- Sent- contains all messages delivered to the mail server;
- Remote- contains deleted letters;
- drafts- contains draft letters.

The user can create their own folders to store thematically grouped emails.

In the lower left part of the window there is a list of contacts, which provides access to information stored in the "Address Book" database (e-mail addresses, phone numbers, etc.).

The right window is divided into two parts. At the top, a list of messages stored in the selected folder is displayed.

The content of the selected message is displayed at the bottom of the right window.

E-mail with Web interface. Some mail servers provide users with the ability to work with e-mail using a Web interface. Work with Webmail can be done with any browser. An essential feature of Web mail is that all messages are permanently stored on a remote mail server, and not on the user's local computer.

Many Web mail servers offer anyone who wants to register a free mailbox. Registered users must enter their login and password, after which they can log into the mail system. For new users, a registration procedure is offered (Fig. 6.15).

Rice. 6.15. Login to Webmail

test questions

1. What are the advantages of email over regular mail?

2. What are the parts of an email address?

3. How does email work?

Tasks for self-fulfillment

6.6. Short answer question. Record the e-mail address registered by user fio on the zmail.ru mail server.

File archives

File archive servers. Tens of thousands of Internet servers are file archive servers, and they store hundreds of millions of files various types(programs, device drivers, graphics and sound files, etc.). The presence of such file archive servers is very convenient for users, since many of the necessary files can be "downloaded" directly from the Internet.

File servers are supported by many software companies and computer hardware manufacturers and peripherals. The software hosted on such servers is freely distributed or shareware, and therefore, by "downloading" a particular file, the user does not violate the software copyright law.

File download managers. For the convenience of users, many file archive servers (freeware.ru, www.freesoft.ru, www.download.ru) have a Web interface, which allows working with them using browsers. Browsers are integrated systems for working with various Internet information resources and therefore include file download managers.

However, it is more convenient to work with file archives using specialized file download managers that allow you to continue downloading a file after the connection to the server is broken. File download managers provide the user with detailed information in numerical and graphical form about the process of downloading a file (file size, volume of the downloaded part, including percentage, download speed, elapsed and remaining download time, etc.).

Some file download managers achieve an increase in download speed by splitting the file into parts and downloading all the parts at the same time. For example, in the FlashGet file download manager, the process of downloading each part of the file is presented in graphical form at the bottom of the application window (Fig. 6.16).

The address of the file on the file archive server. Access to files on file archive servers is possible both via the HTTP protocol and the special FTP file transfer protocol ( File Transfer protocol). The FTP protocol allows you to not only download files from remote servers file archives to the local computer, but vice versa, to transfer files from the local computer to a remote server.

File address includes how the file is accessed and the name of the Internet server where the file is located.

If the FTP file transfer protocol is used as a way to access the file.exe file stored on the ftp.metodist.ru server, then the file address will be written as follows:

ftp://ftp.methodist.ru/file.exe

test questions

1. What kind of files are usually stored on file archive servers?

2. What parts does the file address on the file archive server consist of?

Tasks for self-fulfillment

6.7. Short answer question. Write down the address of the program.exe file stored on a computer registered in the first-level domain sh, the second-level domain schools and having its own name ftp.

Chatting in Internet

Recently, real-time communication on the Internet has become more and more widespread. Increasing data transfer speeds and increased computer performance give users the ability not only to exchange real-time text messages, but also to make audio and video communications.

Real time communication servers. There are thousands of servers on the Internet that implement real-time communication. Any user can connect to such a server and start a conversation with one of the visitors of this server or participate in a group meeting.

The easiest way to communicate "talk", or chat(English chat) is an exchange of messages typed from the keyboard. You type a message on the keyboard and it pops up in a window that all meeting participants can see at the same time.

If your computer, as well as the computers of the interlocutors, are equipped with sound card, microphone and headphones or speakers, you can exchange audio messages. However, a "live" conversation is possible simultaneously only between two interlocutors.

In order for you to be able to see each other, i.e. exchange video images, Web cameras must be connected to the computers.

Interactive communication using the ICQ system. In recent years, interactive communication through ICQ servers has become very popular (this three-letter abbreviation is formed from the consonance of the words "I seek you" - "I'm looking for you").

The ICQ interactive communication system integrates various forms of communication: e-mail, text messaging (chat), Internet telephony, file transfer, searching for people on the network, etc. (Fig. 6.17).

Rice. 6.17. Interactive communication program ICQ

There are currently almost 200 million registered users in the ICQ system, with each user having a unique identification number. After connecting to the Internet, the user can start communication with any user registered in the ICQ system and currently connected to the Internet.

Internet telephony. Internet telephony is used to transmit voice data over the Internet computer network. Internet telephony providers, using special equipment, connect the Internet computer network and the usual telephone network. The user can use Internet telephony services and make a call directly from a computer (see Fig. 6.18) or from a regular phone, having previously dialed the number of an Internet telephony provider.

It is advantageous to use Internet telephony for calls to remote settlements and countries of the world, since a minute of such communication is much cheaper than long-distance and international telephone communication tariffs.

test questions

1. What forms of real-time communication exist on the Internet?

Mobile Internet

Mobile telephone network. At present, the mobile telephone network has covered almost the entire world, and the number of mobile phone users is approaching one billion people. The exchange of information between mobile phones is carried out using a network consisting of station antennas cellular communication interconnected by communication channels.

Network mobile communications allows you to transmit not only voice messages, but also data. Using mobile phones, you can exchange short text messages (SMS) as well as multimedia messages (MMS), which allow you to send phone tones and pictures (such as photos taken with the phone's built-in camera).

Data exchange between the mobile telephone network and the Internet computer network. The mobile telephone network and the Internet computer network allow the transmission of data and voice messages, and therefore it is advisable to combine their information resources. Mobile phone operators and Internet providers provide the ability to transfer data between these networks (Fig. 6.18).

The exchange of data between networks allows, for example, mobile phone send e-mail messages to a mailbox on the Internet, and from a computer connected to the Internet, send SMS messages to a mobile phone.

Internet access using a mobile phone. Many mobile phone models have a built-in modem, so for wireless Internet access it is enough to connect a mobile phone to a computer and call the provider. After connecting your computer to the Internet, you can "surf" the World Wide Web, work with e-mail, "download" files and use any other Internet resources, as with a normal cable connection. The disadvantage of such a connection is the low data transfer rate (no more than 9.6 Kbps) and the high cost per minute of connection.

Full-fledged high-speed Internet access from a mobile phone can be achieved using GPRS technology, at which the maximum possible data transfer rate is 170 Kbps (this is approximately 3 times faster than access via dial-up telephone lines). Importantly, this technology provides immediate access to the Internet, without the need to call an ISP, and allows you to simultaneously talk on a mobile phone and exchange data between a computer and the Internet.

Connecting a mobile phone to a computer can be done in various ways: using a cable to a COM port, using a cable to a USB port, or wirelessly to an infrared port (Fig. 6.19).

To access Internet information resources directly from mobile phones, you can use WAP browsers. WAP sites are specially adapted to the capabilities of a mobile phone (two-color graphics, small screen and small memory) and contain news, weather forecast, exchange rates, etc. From WAP sites, you can send an e-mail message or participate in a WAP chat.

test questions

1. What is the difference between Internet telephony and mobile Internet?

2. What data can be transferred from the mobile telephone network to the Internet computer network? From the Internet to a mobile network?

Audio and video on the Internet

Sound and video files have a large information volume. Transferring such files over computer networks in standard digital formats requires high-bandwidth communication lines. High quality digital stereo sound with a sampling rate of 48,000 times per second and a coding depth of 16 bits requires a bit rate equal to:

16 bits × 48,000 s -1 = 1,536,000 bps = 1500 kbps » 1.5 Mbps.

Television-standard digital video requires a data rate of about 240 Mbps to transmit an image.

To reduce the volume of audio and video files without a visible loss of quality, special file compression methods are used, based on the removal of audio or video information that is not perceived by a person.

Streaming audio and video. Streaming audio and video technologies have become widespread on the Internet. These technologies transfer audio and video files piece by piece to the buffer of the local computer, which makes it possible to stream them even when using a dial-up connection. Reducing the link rate may result in temporary audio dropouts or dropped video frames.

Multimedia players (Windows Media Player, WinAmp, etc.) are used to listen to streaming audio and view streaming video. During playback of a streaming media file, the user receives information about the bit rate and can adjust the playback quality.

There are quite a few radio and television stations that broadcast over the Internet. Web-cameras installed in various parts of the world (on city streets, in museums, in nature reserves, etc.) and continuously transmitting an image are very popular (Fig. 6.20).

test questions

1.Why is it necessary to compress audio and video files when transferring over the Internet?

What is the World Wide Web?

The web, or "web", is a collection of interconnected pages with specific information. Each such page can contain text, images, video, audio and various other objects. But besides this, there are so-called hyperlinks on web pages. Each such link points to a different page, which is located on some other computer on the Internet.

Various information resources, which are interconnected by means of telecommunications and are based on a hypertext representation of data, form the World Wide Web (World Wide Web, or WWW for short).

Hyperlinks link pages that are located on different computers located in different parts of the world. A huge number of computers that are united in one network is the Internet, and the "World Wide Web" is a huge number of web pages hosted on network computers.

Each web page on the Internet has an address - URL (Eng. Uniform Resource Locator - a unique address, name). It is at the address that you can find any page.

How was the World Wide Web created?

On March 12, 1989, Tim Berners-Lee presented to the CERN leadership a project for a unified system for organizing, storing and sharing information, which was supposed to solve the problem of sharing knowledge and experience between the Center's employees. The problem of access to information on different computers Berners-Lee's employees suggested solving it with the help of browser programs that provide access to the server computer where hypertext information is stored. After the successful implementation of the project, Berners-Lee was able to convince the rest of the world to use uniform Internet communication standards using the Hypertext Transfer Protocol (HTTP) and Universal Markup Language (HTML) standards.

It should be noted that Tim Berners-Lee was not the first creator of the Internet. The first system of protocols that provide data transfer between networked computers was developed by employees of the US Defense Advanced Research Projects Agency (DARPA) Winton Cerf and Robert Kahn in the late 60s - early 70s of the last century. Berners-Lee only suggested using the capabilities of computer networks to create new system organization of information and access to it.

What was the prototype of the World Wide Web?

Back in the 60s of the XX century, the US Department of Defense set the task of developing a reliable system for transmitting information in case of war. The US Advanced Research Projects Agency (ARPA) proposed to develop a computer network for this. They called it ARPANET (Advanced Research Projects Agency Network). The project brought together four scientific institutions - the University of Los Angeles, the Stanford Research Institute and the Universities of Santa Barbara and Utah. All work was funded by the US Department of Defense.

First data transfer computer network took place in 1969. A professor at the University of Los Angeles with his students tried to enter the Stanford computer and pass the word "login". Only the first two letters, L and O, were successfully transmitted. When they typed the letter G, the communication system failed, but the Internet revolution took place.

By 1971, a network with 23 users was established in the USA. The first program for sending e-mail over the network was developed. And in 1973, University College London and Government Services in Norway joined the network, and the network became international. In 1977, the number of Internet users reached 100, in 1984 - 1000, in 1986 there were already more than 5000, in 1989 - more than 100,000. In 1997, there were already 19.5 million Internet users.

Some sources indicate the date of the appearance of the World Wide Web a day later - March 13, 1989.

Hello, dear readers of the blog site. We all live in the era of the global Internet and use the terms site, web, www (World Wide Web - World Wide Web, global network) quite often and without really going into what it is.

I observe the same thing with other authors, and even ordinary interlocutors. “Website”, “Internet”, “network” or the abbreviation “WWW” have become so common concepts for us that it doesn’t even occur to think about their essence. However, the first website was born only some twenty years ago. What is the Internet?

After all, it has a rather long history, however, before the advent of the global network (WWW), 99.9% of the world's inhabitants did not even suspect its existence, because it was the lot of specialists and enthusiasts. Now even the Eskimos know about the World Wide Web, in whose language this word is identified with the ability of shamans to find answers in the layers of the universe. So let's discover for ourselves - what is the Internet, a website, the World Wide Web, and everything else.

What is the Internet and its difference from the global web WWW

The most remarkable fact that can now be stated is that The Internet has no owner. In fact, this is an association of individual locales (thanks to the once common standards adopted, namely the TCP / IP protocol), which is maintained by network providers.

It is believed that due to the ever-increasing media traffic (video and other heavy content moving in tons on the network), the Internet will soon collapse due to its currently limited bandwidth. The main problem in this regard is the upgrade of the network equipment that makes up the global web to a faster one, which is primarily constrained by the additional costs required. But I think that the problem will be solved as the collapse matures, and there are already separate network segments operating at high speeds.

In general, in light of the fact that the Internet is essentially nobody's, it should be mentioned that many states, trying to introduce censorship in the global network, want to identify it (namely, its most popular component of the WWW at the moment) with.

But there is really no ground under this desire, because The Internet is just a means of communication or, in other words, a storage medium comparable to a telephone or even plain paper. Try to sanction the paper or its distribution around the planet. Separate sanctions by individual states, in fact, can only be applied to sites (islands of information on the network) that become available to users through the World Wide Web.

The first prerequisites for the creation of the global web and the Internet were taken ... What year do you think? Surprisingly, but already in the dense 1957. Naturally, the military (and, of course, the United States, well, where without them) needed such a network for communication in the event of the deployment of hostilities using nuclear weapons. It took quite a long time to create a network (about 12 years), but this is quite understandable by the fact that at that time computers were in their infancy.

But nevertheless, their power was quite enough to get an opportunity between the military departments and leading US universities by 1971. Thus, the Email transfer protocol has become the first way to use the internet for user needs. After a couple more about what the Internet is already learned across the ocean. By the beginning of the 80s, the main data transfer protocols (mail, ) were standardized, as well as the protocol for the so-called Usenet news conferences, which was similar to mail, but allowed to organize something similar to forums.

A few years later, the idea of ​​​​creating a domain name system (DNS - will play a crucial role in the development of the WWW) appeared and the world's first protocol for communicating over the Internet in real time - IRC (in Russian colloquial - irka) appeared. He allowed to chat online. Fiction, which was accessible and interesting to a very, very small number of inhabitants of the planet Earth. But that's just for now.

At the turn of the 80s and 90s, such significant events took place in the history of infrastructure development that they, in fact, predetermined its future fate. In general, such a spread of the global network in the minds of modern inhabitants of the planet is due to almost one single person - Tim Berners-Lee:

Berners-Lee is an Englishman born to two mathematicians who dedicated their lives to building one of the world's first computers. It was thanks to him that the world learned what the Internet, website, e-mail, etc. are. Initially, he created the World Wide Web WWW (World Wide Web) for the needs of nuclear research at CERN (the same collider is located with them). The challenge was to conveniently place all of the group's scientific information on their own network.

To solve this problem, he came up with everything that is now the fundamental elements of the WWW (what we consider the Internet, without understanding its essence a little). He took as a basis the principle of organizing information, called. What it is? This principle was invented long before that and consisted in organizing the text in such a way that the linearity of the narration was replaced by the ability to navigate through different links (links).

The Internet is hypertext, hyperlinks, URLs and hardware

Thanks to this, hypertext can be read in different sequences, thereby obtaining various variants of linear text (well, you, as Internet users with experience, should now be clear and obvious, but then it was a revolution). In the role of hypertext nodes should have been, which we now call simply links.

As a result, all the information that now exists in computers can be represented as one large hypertext, which includes countless nodes (hyperlinks). Everything that was developed by Tim Berners-Lee was transferred from the CERN local grid to what we today call the Internet, after which the Web (web) began to gain popularity at a frantic pace (the first fifty million users of the World Wide Web were registered in just over a first five years of existence).

But to implement the principle of hypertext and hyperlinks, it was necessary to create and develop several things from scratch at once. Firstly, a new data transfer protocol was needed, which has become known to all of you now HTTP protocol(at the beginning of the addresses of all web sites you will find a mention of it or its secure HTTPs version).

Secondly, it was developed from scratch, the abbreviation of which is now known to all webmasters in the world. So, we got tools for data transfer and creating sites (a set of web pages or web documents). But how to refer to these same documents?

The first one allowed to identify the document on a separate server (site), and the second one allowed to add a domain name (received and unambiguously indicating that the document belongs to a website hosted on a specific server) or an IP address (a unique digital identifier of absolutely all devices in the global or local network). Read more about the link provided.

It remains to take just one step to ensure that the World Wide Web WWW finally works and becomes in demand by users. Do you know what?

Well, of course, a program was needed that could display the contents of any web page requested on the Internet (using a URL address) on the user's computer. It became such a program. If we talk about today, then there are not so many major players in this market, and I managed to write about all of them in small review:

1. (IE, MSIE) - the old guard is still in the ranks
2. (Mazila Firefox) - another veteran is not going to give up positions without a fight
3. (Google Chrome) - an ambitious newcomer who managed to take the lead in the shortest possible time
4. - a browser loved by many in Runet, but gradually losing popularity
5. - a messenger from the apple camp

Timothy John Berners-Lee independently wrote the program for the world's first Internet browser and called it, without further ado, the World Wide Web. Although this was not the limit of perfection, however, it was with this browser that the victorious march of the World Wide Web WWW around the planet began.

In general, of course, it is striking that all the necessary tools for the modern Internet (meaning its most popular component) were created by just one person in such a short time. Bravo.

A little later, the first graphical browser Mosaic appeared, from which many of the modern browsers (Mazila and Explorer) also originate. It was the Mosaic that became the drop that was not enough to interest in the internet(namely, to the World Wide Web) from ordinary inhabitants of the planet Earth. A graphical browser is a completely different matter than a text browser. Everyone loves to look at pictures and only a few like to read.

Remarkably, Berners-Lee did not receive any terribly large amounts of money, which, for example, he received or received as a result, although he probably did more for the global network.

Yes, over time in addition to that developed by Berners-Lee Html language also added. Thanks to this, some of the operators in Html were no longer needed, and they were replaced by much more flexible cascading style sheet tools, which made it possible to significantly increase the attractiveness and design flexibility of the sites being created now. Although in learning the rules of CSS are, of course, more complex than the markup language. However, beauty requires sacrifice.

How are the Internet and the global network arranged from the inside?

But let's see what is web (www) and how information is posted on the Internet. Here we will come face to face with the very phenomenon called website (web is a grid, and site is a place). So, what is a “place on the web” (an analogue of a place under the sun in real life) and how to actually get it.

What is inte? So, it consists of channel-forming devices (routers, switches) that are invisible and not of great importance to users. The WWW network (what we call the Web or the World Wide Web) consists of millions of web servers, which are programs running on slightly modified computers, which in turn must be connected (24/7) to the global web. and use the HTTP protocol for communication.

The web server (program) receives a request (most often from the browser of the user who opens the link or entered the Url in the address bar) to open a document hosted on this server itself. The document in the simplest case is a physical file (with the html extension, for example), which lies on the server's hard drive.

In a more complex case (when using ), the requested document will be generated programmatically on the fly.

To view the requested page of the site, special software is used on the client (user) side called a browser, which can render the downloaded hypertext fragment in a digestible form on the display device where this same browser is installed (PC, phone, tablet, etc.). ). In general, everything is simple, if you do not go into details.

Previously, each individual website was hosted physically on a separate computer. This was mainly due to the weak computing power of the PCs available at that time. But in any case, a computer with a web server program and a website hosted on it must be connected to the Internet around the clock. It is quite difficult and expensive to do this at home, so they usually use the services of specialized hosting companies to store web sites.

Hosting service due to the popularity of the WWW is now quite in demand. Thanks to the growing power of modern PCs over time, hosters have the opportunity to host many websites on one physical computer (virtual hosting), and hosting one site on one physical PC has become known as a service.

When using virtual hosting, all websites hosted on a computer (the one called the server) can be assigned one IP address, or there can be a separate one for each. This does not change the essence and can only indirectly affect the Website hosted there (a bad neighborhood on the same IP can have a bad effect on - search engines sometimes treat everyone with the same brush).

Now let's talk a little about domain names websites and their importance on the World Wide Web. Every resource on the Internet has its own domain name. Moreover, a situation may arise when the same site may have several domain names (as a result, mirrors or aliases are obtained), and also, for example, the same domain name may be used for many resources.

Also for some serious resources there is such a thing as mirrors. In this case, the site files may be located on different physical computers, and the resources themselves may have different domain names. But these are all the nuances that only confuse novice users.

The World Wide Web(English) world wide web) is a distributed system that provides access to

related documents located on different computers connected to the Internet. The World Wide Web is made up of millions of web servers. Most of the resources on the World Wide Web are hypertext. Hypertext documents posted on the World Wide Web are called web pages. Several web pages that share a common theme, design, and links, and are usually located on the same web server, are called a web site. To download and view web pages, special programs are used - browsers. The World Wide Web has caused a real revolution in information technology and a boom in the development of the Internet. Often, when talking about the Internet, they mean the World Wide Web, but it is important to understand that this is not the same thing. The word is also used to refer to the World Wide Web. web(English) web) and the abbreviation www.