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• Introduction 3
• 4
• 1.1. Basic provisions of the network structure 4
• 1.2. Internet access 4
• 6
• 2.1. Remote access (telnet) 6
• 2.2. File transfer (ftp) 6
• 2.3. Email (e-mail) 7
• 2.4. Bulletin boards (USENET news) 7
• 2.5. Search for data and programs (Archie) 7
• 2.6. Gopher shell 8
• Conclusion 11
• Bibliography 12

Introduction

The Internet is a global computer network covering the whole world. The Internet forms, as it were, the core that provides communication between various information networks belonging to various institutions around the world, one with another.

In fact, the Internet is not just a network - it is a structure that connects conventional networks. The Internet stands for ``Network of Networks''. What does the Internet include? The question is not easy. The answer to this changes over time. At first, the answer would be quite simple: ``all networks using the IP protocol that cooperate to form a single network of their users"". This would include various departmental networks, many regional networks, educational networks, and some foreign networks (outside the US).

A little later, the attractiveness of the Internet was realized by some non-IP networks. They wanted to provide its services to their customers and developed methods to connect these ``weird'' networks (eg Bitnet, DECnet, etc.) to the Internet. At first, these connections, called gateways, served only to transfer e-mail. However, some of them have developed ways to transfer other services as well. Are these networks part of the Internet? Yes and no. It all depends on whether they want it themselves.

If earlier the network was used exclusively as a medium for transferring files and e-mail messages, today more complex tasks of distributed access to resources are being solved. About ten years ago, shells were created that support the functions of network search and access to distributed information resources, electronic archives.

The Internet, once exclusively for research and academic groups whose interests ranged from access to supercomputers, is becoming increasingly popular in the business world.

With low service costs (often only a flat monthly fee for the lines or telephone used), users can access commercial and non-commercial information services. In the archives of free access on the Internet, you can find information on almost all areas human activity, from new scientific discoveries to tomorrow's weather forecast.

In addition, the Internet provides unique opportunities cheap, reliable and private global communications around the world. This turns out to be very convenient for firms with their branches around the world, multinational corporations and management structures. Typically, using the Internet infrastructure for international communications is much cheaper than direct computer communications via satellite or telephone.

The Internet is currently experiencing an upswing. Today, the Internet has about 20 million subscribers in more than 150 countries around the world. The size of the network increases by 7-10% monthly.

The purpose of this work is to review and study the main features of the Internet.

Chapter 1. Basic features of the Internet

1.1. Basic provisions of the network structure

Every user on the Internet has their own opinion about how the network should function. Internet users express their opinions at IETF (Internet Engineering Task Force) engineering committee meetings. IETF is another public body; it meets regularly to discuss current technical and organizational problems of the Internet. If a problem of sufficient importance arises, the IETF forms a working group to study it further. (In practice, "important enough" usually means that there are enough volunteers to form a working group.) Anyone can attend IETF meetings and serve on working groups; it is important that it works. Working groups perform many different functions - from issuing documentation and deciding how networks should interact with each other in specific situations, to changing the values ​​of bits in a certain standard. The working group usually draws up a report. This can either be documentation provided to the public with recommendations that are not required to be followed, or a proposal that is sent to the IAB for adoption as a standard.

Now the Internet consists of more than 20 thousand interconnected networks.

1.2. Internet access

Internet access is usually obtained through service providers. These vendors sell different kinds services, each with its own advantages and disadvantages. Just like when buying a garden wheelbarrow (in the original - a car), you decide what qualities it should have, how much you can afford to pay for it, and, based on this, choose the appropriate option from the offered set.

But before starting to act in this direction, i.e. get a list of Internet providers, read and select, contact them, find out if you already have access to the Internet without knowing it. This may well take place - not so often in Russia, not so rarely in the USA. If your organization or institution (institution, company) already has access to the Internet, then it is unlikely that you will be able to get better personal access to the network than your organization.

In other words, if you already have access to the Internet, you won't have to pay out of pocket, you won't have to fuss around service providers, etc., you just have to learn how to use what you already have.

If your organization does not yet have access to the Internet, or actually has, but, the trouble is, not your unit (laboratory, department, faculty), you just have to observe and figure out how many more potential users there are among your colleagues, perhaps talk to them and get support, make a proposal and/or submit a request to higher management.

There are (although this is, alas, very rare so far) still possible to access the Internet not through its direct distributors, without extra costs.

First - look in public libraries: some (central) have a service called Freenet - a free (free) network. It is a community-based information system, usually with dial-up access to the Internet by telephone.

The second way is useful for young people living in Western countries, or in our central cities. Become a student, enter a Western university or college organized in Russia together with the West. And choose the appropriate specialty or sign up for courses that will allow you to get to the coveted computer with Internet access. For example, learn how to weave bast shoes - only then you will have something to have fun when you go crazy from continuous work on the network. And when you learn, you will have one more argument to the authorities in favor of providing you with access to the Internet: the network needs a database with instructions for weaving bast shoes, without them they are like without hands. This contribution cannot be overestimated by management.

Chapter 2. Main features of the global Internet

Consider the most popular features of the Internet. These services are supported by the standard. For a more specific description of the commands, see the documentation for the respective software. For most, however, the information and explanations found in the interactive help systems (help-ax) or description files will suffice.

2.1. Remote access (telnet)

Remote Login - remote access - work on a remote computer in the mode when your computer emulates the terminal of a remote computer, i.e. you can do everything (or almost everything) that you can do from the usual terminal of that machine. Traffic related to this type of networking, on average, is about 19% of all network traffic. Start session remote access you can on UNIX by issuing the telnet command and specifying the name of the machine you want to work from. If you omit the port number, your computer emulates that machine's terminal by default and you log in as normal. Specifying the port number allows you to communicate with non-standard servers, interfaces.

To use this wonderful network feature, you must have access to the Internet of a class no lower than dial-up access.

2.2. File transfer (ftp)

ftp - File Transfer Protocol - a protocol for transferring files - a protocol that defines the rules for transferring files from one computer to another.

ftp is also the name of a software program. Uses the ftp protocol to transfer files.

In terms of application, ftp is in many ways similar to telnet. Those. to work with ftp, you need to have access to the remote machine from which you want to download files to yourself, i.e. have a login name and know the corresponding password. Access must be at least dial-up (on call). To use ftp, you need to issue the ftp command with the name of the host you want to log into. ftp also allows (it has its own set of commands) to search for a file on a remote machine, that is, move from directory to directory, view the contents of these directories, files. Allows you to send both files and their groups, as well as entire directories, together with all subdirectories nested to any depth. Allows transfer of data in files either as binary information or as ASCII (i.e. text). ASCII transfer enables automatic recoding of data when transferring text to a computer with a different alphabet encoding, etc., which preserves the readable appearance of the text. It is possible to compress data during transfer and then decompress it back to its original form.

It is also possible to use ftp in batch mode via e-mail on some servers, but the lack of a direct dialogue is very inconvenient and slows down the work a lot - for lack of a better it is quite tolerable.

2.3. Email (e-mail)

This is the most popular use of the Internet in our country today. Estimates say that there are over 50 million e-mail users in the world. In general, in the world, e-mail traffic (smtp protocol) occupies only 3.7% of the entire network. Its popularity is explained both by urgent requirements and by the fact that most connections are connections of the ``access on call'' class (from a modem), and in Russia, in general, in the vast majority of cases, UUCP access. E-mail is available with any kind of access to the Internet.

E-mail (Electronic mail) - e-mail (common people - an electronic analogue of regular mail. With it, you can send messages, receive them in your electronic mailbox, answer letters from your correspondents automatically using their addresses, based on their letters , send copies of your letter to several recipients at once, forward the received letter to another address, use logical names instead of addresses (numerical or domain names), create several mailbox subsections for various kinds of correspondence, include text files in letters, use the “mail reflectors” system for discussions with a group of your correspondents, etc. From the Internet, you can send mail to adjacent networks if you know the address of the appropriate gateway, its format of calls, and the address on that network.

2.4. Bulletin boards (USENET news)

These are the so-called network news or discussion clubs. They give you the ability to read and post to public (open) discussion groups. In fact, they are a network version of bulletin board systems (BBS: Bulletin Board System), originally running on dial-up machines. ``News'' are messages addressed to the general public and not to a specific addressee. These messages can be of a completely different nature: from a message about a great event that has just happened, to a question about Buridan's donkey. Network nodes involved in the maintenance of the news system, upon receipt of the news package, send it to their neighbors, if they have not yet received such news. An avalanche-like broadcast is obtained, which ensures the rapid distribution of a news message throughout the network.

2.5. Search for data and programs (Archie)

Archie is a system for searching and issuing information about the location of public files via anonymous ftp. A system that supports this type of service regularly collects from its wards (anonymous ftp servers) information about the files contained there: lists of files by directories, lists of directories, as well as files with a brief description of what is what. Allows you to search by file names (directories) and descriptive files, namely by the words contained there. For example, you give an instruction (command) to find a file with exactly that name or with a name that matches the specified pattern, and Archie gives you a response where there is one. Or you can search by semantic words, which should be contained in a brief description of this file or program, compiled by its creator. Of course, compiling a worthy (short, accurate, intelligent, adequate) description of your brainchild remains entirely on the conscience of the product creator, which gives rise to some freedom, and therefore, in some cases, abuse of users' trust or simply neglect it is possible. Archie is accessed via Archie servers (eg archie.doc.ic.ac.uk (this is in the UK)). Full-blooded use of Archie requires Internet access, at least a dial-in class. Possibility of indirect access via e-mail (!). See help in Archie itself for more details. Help is also available at e-mail. Send an e-mail to a name [email protected] server.domain.name containing a single line: help. Get a response containing short description command systems.

2.6. Gopher shell

Gopher is an Internet capability integrator. It allows you to use all the services provided by the Internet in a convenient form. The shell is organized in the form of many nested menus at different depths, so you just have to select the desired item and press enter. Everything your heart desires is available in this form: telnet sessions, ftp, e-mail, etc. etc. Also included in this shell are interfaces with such servers, with which it is simply impossible to communicate manually due to their machine-oriented protocol. Gopher servers are becoming widespread. Traffic is 1.6% of the total in the network. From one server, you can enter others anywhere, the ease of communication does not change from this. In this way, you can surf the entire network without experiencing headaches from changing command systems and data and resource structures. The main thing is not to forget this whole path, not to cross oneself when traveling, and at the end of everything, carefully go back, closing the started work sessions. Gopher can be found in the pub/gopher directory at box.micro.umn.edu via anonymous ftp. Gopher must be installed directly on your network workstation and is purely interactive. Your access to the Internet should be no worse than access on a call.

Table 1

Conclusion

The Internet continues to develop with unrelenting intensity, in fact erasing the restriction on the distribution and receipt of information in the world. However, in this ocean of information it is not very easy to find required document. It should also be borne in mind that new servers appear in the network along with long-standing servers.

In many ways, the Internet is like religious organization: it has a council of elders, each user of the network can have their own opinion about the principles of its work and take part in network management. The Internet has no president, no chief engineer, no Pope. Internet networks may have presidents and other top officials, but that's a completely different matter. In general, there is no single authoritarian figure on the Internet.

Currently, the Internet is experiencing a period of recovery, largely due to the active support from the governments of European countries and the United States. About $1-2 billion is allocated annually in the US to build new network infrastructure. Research in the field of network communications is also funded by the governments of Great Britain, Sweden, Finland, and Germany.

However, public funding is only a small part of the incoming funds. the "commercialization" of the network is becoming more and more noticeable (it is expected that 80-90% of the funds will come from the private sector).

The Internet is a constantly developing network, let's hope that our country will not lag behind progress and meet the 21st century with dignity.

Bibliography

1. All about INTERNET. Manual and catalog. Ed Krol. BHV, Kyiv.

2. Dontsov, D. Windows XP. Easy start [Text] / D. Dontsov - St. Petersburg. Peter, 2005.-144p.:ill.

3. Zhurin, A.A. The most modern tutorial for working on a computer [Text] / A.A. Zhurin. - M .: LLC "Publishing house AST": "AQUARIUM BUK", 2003. - 607 p.: ill.

4. Magazine on personal computers PC Magazine Russian Edition. №1-12 - 2006

5. Magazine on personal computers PC Magazine Russian Edition. №1-4 - 2007

6. Informatics [Text]: basic course: studies. manual for universities / ed. S.V. Simonovich. - 2nd ed. - St. Petersburg: Peter, 2005. - 640 p.: ill.

7. Informatics [Text]: workshop on computer technology: tutorial for universities / N. V. Makarova, E. I. Kultyshev, A. G. Stepanov and others; ed. N.V. Makarova. - Ed. 3rd, revised. - M.: Finance and statistics, 2005. - 256 p.: ill.

8. Informatics [Text]: textbook for universities / N. V. Makarova, L. A. Matveev, V. L. Broido et al.; ed. N.V. Makarova. - Ed. 3rd, revised. - M.: Finance and statistics, 2006. - 768 p.: ill.

9. Computer weekly "Computerra". No. 120 - 167 - 2006

10. Computer weekly "Computerra". No. 180 - 190 - 2007

11. Kondratiev, G. G. Windows XP and useful programs: installation and configuration [Text] / Ed. 1st. St. Petersburg: Peter, 2005.-- 336 p.: ill.

12. Leontiev, V.P. Choosing a computer, mastering Windows XP [Text] / V.P. Leontiev - M.: OLMA-PRESS, 2005. - 348 p.: ill.

13. Leontiev, V.P. The latest encyclopedia of a personal computer [Text] / V.P. Leontiev - M.: OLMA-PRESS, 2006. - 800 p.: ill.

14. Leontiev, V.P. Mastering Windows XP [Text] / V.P. Leontiev - M.: OLMA-PRESS, 2005. - 219 p.: ill.

15. Leontiev, V.P. Learning to work with Windows XP [Text] / V.P. Leontiev - M.: Binom, 2004. - 47 p.: ill.

16. Russian computer library URL: http://rusdoc.df.ru

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The Internet provides its users with a variety of services and opportunities (services). Let's list the main ones.

1. World Wide Web - the main information service.

World Wide Web (WWW, World Wide Web) is a hypertext, or rather, hypermedia information system for searching for Internet resources and accessing them.

Hypertext is an information structure that allows you to establish semantic links between text elements on a computer screen in such a way that you can easily navigate from one element to another. In practice, in hypertext, some words are highlighted by underlining or coloring in a different color. Highlighting a word indicates that there is a connection between this word and some document in which the topic associated with the highlighted word is considered in more detail.

Hypermedia is what happens if in the definition of hypertext the word "text" is replaced by "any kind of information": sound, graphics, video. Such hypermedia links are possible because, along with textual information, any other binary information can also be linked, such as encoded sound or graphics. So, if the program displays a map of the world and if the user selects a continent on this map with the mouse, the program can also give graphic, sound and text information about it.

The WWW system is built on a special data transfer protocol called the HyperText Transfer Protocol (HTTP). All contents of the WWW system consist of WWW pages.

WWW pages are hypermedia documents of the World Wide Web system. They are created using the Hypertext Markup Language (HTML).

HTML allows you to add text documents special command fragments - tags (English tag - "label, label") in such a way that it becomes possible to associate other texts, graphics, sound and video with these documents, set headings of various levels, divide text into paragraphs, build tables, etc. d. For example, the title of a document might look like this:

In fact, one WWW page usually consists of a set of hypermedia documents located on the same server, intertwined with mutual links and related in meaning (for example, containing information about one educational institution or about one museum). Each page document, in turn, can contain multiple screen pages of text and illustrations. Each WWW-page has its own "title page" (eng. "homepage") - a hypermedia document containing links to the main components of the page. "Cover page" addresses are distributed on the Internet as page addresses.

Personal pages - such WWW-pages that do not belong to firms or organizations, but to individuals. The content and design of such a page depends only on its author.

When working with the WWW system, users deal with system client programs called browsers.

Browsers (eng. browse - leaf through, view) - programs with which the user organizes a dialogue with the WWW system: browses WWW pages, interacts with WWW servers and other resources on the Internet.

There are hundreds of browser programs. The most popular browsers are Netscape Navigator and Microsoft Internet Explorer. WWW browsers can communicate with any type of server using their own protocols. The WWW browser displays information received from any server in a standard, easy-to-read form. At the same time, switching from one protocol to another for the user often goes unnoticed.

Email.

E-mail (Electronic mail, English mail - mail, abbr. e-mail) serves to transfer text messages within the Internet, as well as between other email networks. To the text of the letter, modern mail programs allow you to attach sound and graphic files, as well as binary files - programs. When using e-mail, each subscriber is assigned a unique postal address, the format of which is as follows:

<имя пользователя> @ < имя почтового сервера>.

For example: [email protected], where earth is the username, space.com is the computer name, @ is the delimiter "this is commercial".

Messages received by e-mail are stored in a special "mail" computer in the area of ​​\u200b\u200bdisk memory allocated for the recipient (his "mail box"), from where he can upload them and read them using a special client program. To send a message, you need to know the email address of the subscriber. With high-quality communication, an e-mail reaches anywhere in the world within a few minutes. E-mail users strive to adhere to the rules of network etiquette (netiquette), and to express emotions they use schematic images of a human face, the so-called emoticons (English smiley, “smile”), some of which are listed below. Emoticons (look at it with your head tilted to the left)

Currently, more than 2.5 billion people use the Internet and this number is constantly growing. Most of the developed and developing countries are already connected to the worldwide network, and the possibilities of satellite communications show that in the near future the Internet will be extended even to hard-to-reach regions. In a world where globalization comes to the fore in economic, social and political relations, it is impossible to imagine life without this universal means of communication.

Receiving the information

The main opportunity provided by the Internet is communication. The World Wide Web connects all owners of the network. Wherever you are, you can go to any permitted resource, get acquainted with the information, find new people with similar interests. There are also different sites on the Internet, so you can choose which ones suit you best: text sites, sites with video, audio, pictures or photos. Humanity has not yet known such an accessible source of information as the Internet. Now knowledge is not limited by the walls of libraries, not separated by distance, even languages ​​do not become an obstacle, since many translators have been created working online.

All this provides the main advantages of the Internet: you can find almost any information or person in it. And this opens up opportunities for communication and learning without borders. Forums, chats, social networks, instant messengers - all this was created so that anyone in the world could find friends, partners, teachers and students, interlocutors. There are many scientific and educational portals, libraries and repositories of various information about humanity in the global network, which can satisfy the curiosity and thirst for knowledge of any person. With such resources, school and university education in the usual sense of the word may soon lose their significance. It is not for nothing that online courses, seminars, distance learning at school and university are already emerging today, so that each student has access to knowledge in a place convenient for him.

Spread of information

The Internet has almost limitless possibilities to provide users with new information every day and very quickly. The speed of dissemination of information has never been so high: as soon as some high-profile event occurs in the world, a mention of it immediately appears on the Internet, and then spreads at lightning speed to other sites and can become known to a huge number of users in a couple of minutes. In addition, most of this information cannot be hidden or banned, so publicity and freedom of speech are much more relevant concepts online than for print media.

The possibilities of the Internet in the field of business, shopping, freelancing are almost limitless. In the vastness of the global network, you can find and purchase almost any product, order delivery and pay without leaving your home. Here you can also find customers for work, clients, partners, build business relationship on distance. Every year, the level of the network's cash turnover is growing, which means that more and more companies understand the advantages of online business and at least partially bring their companies to the Internet. This is how thousands of stores, websites and resources appear in social networks that sell goods and services. In addition, the global web extends its influence to the entertainment sector: there are games, films, series, entertainment programs, even TV channels are now broadcast not only on TV, but also on the Internet.

A new phenomenon in the life of society at the end of the 20th century was the creation of the global international computer network Internet. This computer network for many people has become a means of quickly obtaining the most various information- electronic copies of newspapers, letters, magazines, books, programs, games and informational news.

The transmission and receipt of information via the Internet has become the most widespread use abroad personal computers. Prompt receipt of a variety of information at home and at work using personal computers becomes available after connecting them to a telephone or telecommunications network.

A computer network is an association of computers in which each computer can transmit information to any other computer connected to the network. The main possibility of computer networks is access to information, documents and information resources stored on computers connected to the network.

Information resources - a set of documents in archives, libraries, funds, data banks and other information systems. In computer networks, information resources stored in a computer can be accessed using other personal computers connected to this network.

By the number of connected computers, networks are divided into local, corporate, regional and global. Accordingly, we can talk about corporate, regional and global information resources available in these computer networks.

A local area network is a network that links computers in one or more adjacent rooms. Examples local networks are classrooms of educational computers in schools, universities, offices and laboratories.

Servers play a leading role in the organization of computing systems and networks. Servers are powerful computers with large disk storage used to store files and programs. Servers are used for the accumulation and transmission of publicly available information in computer networks and usually operate 24 hours a day.

At the same time, at the level of local networks, questions arise about the organization of reliable storage of information and its protection from unauthorized access. To maintain, securely store and protect information on the network, specialists are involved, whose profession is called network administrators.

A regional area network connects computers within a particular region. Examples of regional networks are corporate computer networks in banks and corporations, as well as in industrial and commercial enterprises.

To connect to a regional network of personal computers, you need special means communications - communication channels, modems and network software. As a means of telecommunication between computers, ordinary telephone channels are used, as well as special fiber optic lines communications or satellite radio channels.

Modems are devices for communicating between computers and other computers using communication channels. The functions of modems consist in converting data represented in the computer in the form of 0 and 1 into telephone signals with two carrier frequencies. The main characteristic of a modem is the data transfer rate, measured in bauds.

The speeds of the most common modern modems are 2400, 9600, 14400, 19200, 22800 and 33600 baud. You can use any of these modems for email. To work on the Internet, modems with a transfer rate of at least 19200 baud are required.

at the regional level and large corporations the issues of protection and reliable maintenance of information that forms corporate information resources is a serious problem. Errors in the design and operation of corporate information and computing networks can lead to serious economic damage.

The global network brings together computers located in different countries on different continents of the globe. An example of a global computer network is the international computer network Internet. To connect to the Internet, special network programs are used.

Network programs are programs for gaining access to information, information resources and information systems used in a computer network. Examples of such programs are Microsoft's Internet Explorer and Netscape's Netscape Navigator, which are designed to run on IBM PCs with operating system Windows.

With regard to the Internet, the concept of global information resources available from anywhere on our planet is used. The development of the Internet is the basis for organizing the storage and access to all information accumulated by human society.

The basis of the modern information computer industry and the Internet is a worldwide distributed network. digital libraries WWW - World Wide Web. Electronic libraries in this network are hosted on special servers.

Electronic libraries on the Internet are organized with the help of hypertexts. In the form of hypertexts, a variety of documents, newspapers, magazines, catalogs, price lists, as well as all kinds of information and information search engines and network programs - network computer games, online electronic textbooks, online directories and encyclopedias.

Hypertext is a collection of pages with texts, pictures and links to other pages. Links can be made both to the pages of this hypertext, and to the pages of any other hypertext stored in this computer or even on any other file server registered on the Internet.

To access electronic libraries, special hypertext names are used that act as a server address on the network. The codes indicated in the addresses are approved by the international standard. Example - hypertext name on the Internet of a virtual server training center, which contains an electronic copy of this computer science textbook along with a system of control tests: www.prometey.ankey.#####

In this example, the server name consists of four parts. The first word www is a sign that the server is connected to the Internet. The middle name prometey is the name of the system distance learning Prometheus. The third name ankey is the name of the Ankey corporation that owns this server. The last fourth word ##### is the sector identifier on the Internet.

Examples of electronic libraries on the Internet can serve as servers of various central newspapers, magazines - Izvestia newspaper server, Itogi magazine server, Russian Radio radio station server.

On the Internet you can find several game servers, as well as servers of distance learning centers of leading Moscow and Russian universities - MESI (Moscow State University Economics, Statistics and Informatics) and MIEM (Moscow Institute of Electronics and Mathematics).

E-mail is a way of sending letters using personal computers and telecommunications. A wide variety of text files, images, programs and data sets can be sent as e-mails.

The text of the letter to be sent by e-mail must be prepared on a computer in the form of a text file and formatted in accordance with Internet standards. The generally accepted message format consists of a header and the message itself, which can be played by any text file, picture or program.

A standard email header looks like this:

From: sender's address

To: recipient's address

ss: other shipping addresses

Subject: the subject of the message

An example of a postal address on the Internet: Ca#####@mail.ru

The first name Ca##### is the ID of the mailbox owner. The second name is the address of the mail.ru mail server. Here mail is the identifier of the domestic mail system Mail-Ru, in which any of you can open a free electronic mailbox.

To search for information on the Internet in our country and abroad, several information retrieval systems are used. Among domestic systems, the most famous systems are Aport, Rambler and Yandex, foreign - Altavista, Infoseek, Yahoo.

The search for information on the Internet by these systems is carried out upon request. The simplest queries consist of one or more words in Russian or English, or in another language in which the required documents are written.

The result of a search on the Internet are lists of names and addresses of hypertexts that meet the given queries. For example, for the query "Cayman informatics", search engines will provide a list of all hypertexts available on the Internet that contain the words "Caiming" and "computer science". This list will also include the addresses of servers hosting network electronic textbooks in computer science.

These search engines weekly scan all servers on the Internet and index all found hypertexts, remembering their addresses and the keywords and phrases found in them. For this reason, any information posted on the Internet can be found by queries of interest to us.

global information computer network internet

Hypertext- an information structure that allows you to establish semantic relationships between text elements on a computer screen in such a way that you can easily make transitions from one element to another. In practice, in hypertext, some words are distinguished by underlining or dyeing in a different color. Highlighting a word indicates that there is a connection between this word and some document in which the topic associated with the highlighted word is considered in more detail.

Hypermedia- this is what happens if in the definition of hypertext we replace the word "text" with "any kind of information": sound, graphics, video. Such hypermedia links are possible because, along with textual information, any other binary information can also be linked, such as encoded sound or graphics. So, if the program displays a map of the world and if the user selects a continent on this map with the mouse, the program can also give graphic, sound and text information about it.

The WWW system is built on a special data transfer protocol called HTTP hypertext transfer protocol(pronounced "h-ti-ti-pi", HyperText Transfer Protocol). All contents of the WWW system consist of WWW pages.

The HTML language allows you to add special command fragments to text documents - tags(English) tag- "label, label") in such a way that it becomes possible to associate other texts, graphics, sound and video with these documents, set headings of various levels, divide text into paragraphs, build tables, etc. For example, the title of a document might look like this:

In fact, one WWW-page usually consists of a set of hypermedia documents located on the same server, intertwined with mutual links and related in meaning (for example, containing information about one educational institution or one museum). Each page document, in turn, can contain multiple screen pages of text and illustrations. Each WWW-page has its own "title page" (eng. "homepage") - a hypermedia document containing links to the main components of the page. "Cover page" addresses are distributed on the Internet as page addresses.

When working with the WWW system, users deal with client programs of the system, calledbrowsers.

There are hundreds of browser programs. Most popular browsers: Netscape Navigator and Microsoft Internet Explorer. WWW browsers can communicate with any type of server using their own protocols. The WWW browser displays information received from any server in a standard, easy-to-read form. At the same time, switching from one protocol to another for the user often goes unnoticed.