Internet - a global telecommunications network of information and computing resources. Serves as the physical basis for the World Wide Web. It is often referred to as the World Wide Web, the Global Network, or simply the Network. It represents a dead combination of wax systems, which does not guarantee the quality of communication, but ensures good stability and independence of the functioning of the system as a whole from the operability of any of its sites.
Nowadays, when the word "Internet" is used in everyday life, most often it is the World Wide Web and the information available in it, and not the physical network itself.
By the middle of 2008, the number of users who regularly used the Internet was about 1.5 billion people (about a quarter of the world's population) .
The world computer network Internet together with personal computers forms a technological basis for the development of the international concept of the "World Information Society".
History and time of creation
After the Soviet Union launched an artificial Earth satellite in 1957, the US Department of Defense considered that in the event of a war, America needed a reliable information transfer system. The US Advanced Defense Research Projects Agency (DARPA) has proposed the development of a computer network for this purpose. Development of such a network was entrusted to the University of California in Los Angeles, Stanford Research Center, University of Utah and the University of California in Santa Barbara. The computer network was named ARPANET (English Advanced Research Projects Agency Network), and in 1969, the network united the four mentioned scientific institutions in the framework of the project. All works were funded by the US Department of Defense. Then the ARPANET network began to grow actively and develop, scientists from different fields of science began to use it.
The first ARPANET server was installed on September 1, 1969 at the University of California, Los Angeles. Computer Honeywell DP-516 had 24 KB of RAM.
October 29, 1969 at 21:00 between the first two nodes of the ARPANET network, located at a distance of 640 km - at the University of California Los Angeles (UCLA) and at the Stanford Research Institute (SRI) - held a communication session. Charlie Kline tried to remotely connect to a computer in SRI. The successful transmission of each symbol introduced by his colleague, Bill Duvall (Bill Duvall) from SRI confirmed by phone.
For the first time it was possible to send only three symbols "LOG", after which the network ceased to function. LOG should be the word LOGON (login command). In working condition, the system was returned by 22:30 and the next attempt was successful. It is this date that can be considered the birthday of the Internet .
By 1971, the first program to send e-mail on the network was developed. This program immediately became very popular.
In 1973, the first foreign organizations from Great Britain and Norway were connected to the network via a transatlantic telephone cable, the network became international.
In the 1970s, the network was mainly used to send e-mail, then the first mailing lists, news groups and message boards appeared. However, at that time the network could not easily interact with other networks built on other technical standards. By the end of the 1970s, data transfer protocols began to develop rapidly, which were standardized in 1982-83. John Postel played an active role in the development and standardization of network protocols. On January 1, 1983, the ARPANET network moved from the NCP protocol to TCP / IP, which has been successfully used so far to unify (or, as they say, "layers") networks. It was in 1983 that the term "Internet" was assigned to the ARPANET network.
In 1984, the domain name system (English Domain Name System, DNS) was developed.
In 1984, the ARPANET network had a serious rival: the National Science Foundation of the United States (NSF) established an extensive inter-university network NSFNet (English National Science Foundation Network), which was made up of smaller networks (including the then known Usenet and Bitnet networks) and had much greater bandwidth than ARPANET. About 10 thousand computers connected to this network for a year, the title "Internet" began to smoothly switch to NSFNet.
In 1988, the Internet Relay Chat (IRC) protocol was developed, making it possible to communicate in real time on the Internet (chat).
In 1989, the concept of the World Wide Web was born in Europe, within the walls of the European Council for Nuclear Research (fr. Conseil Européen pour la Recherche Nucléaire, CERN). It was suggested by the famous British scientist Tim Berners-Lee, who also developed the HTTP protocol, the HTML language and URIs within two years.
In 1990, the ARPANET network ceased to exist, completely losing the competition to NSFNet. In the same year, the first connection to the Internet was recorded over the telephone line (so-called dial-up).
In 1991, the World Wide Web became widely available on the Internet, and in 1993 appeared the famous web browser NCSA Mosaic. The World Wide Web was gaining popularity.
In 1995, NSFNet returned to the role of a research network, the routing of all Internet traffic was now handled by network providers, rather than supercomputers of the National Science Foundation.
In the same 1995, the World Wide Web became the main provider of information on the Internet, overtaking the FTP file transfer protocol. The World Wide Web Consortium (W3C) was formed. We can say that the World Wide Web has transformed the Internet and created its modern look. Since 1996, the World Wide Web almost completely replaces the concept of "Internet".
In the 1990s, the Internet combined most of the networks that existed then (although some, like Fidonet, remained isolated). The union looked attractive due to the lack of unified guidance, and also due to the openness of the technical standards of the Internet, which made the networks independent of business and specific companies. By 1997 there were already about 10 million computers on the Internet, over 1 million domain names were registered. The Internet has become a very popular medium for information exchange.
Currently, you can connect to the Internet through communication satellites, radio channels, cable television, telephone, cellular communications, special fiber-optic lines or electric wires. The global network has become an integral part of life in developed and developing countries.
Within five years, the Internet has reached an audience of over 50 million users. Other media needed much more time to achieve such popularity
Initially, the main purpose of the Internet was to find information on the network. If previously the network was used exclusively as a medium for file transfer and e-mail messages, today more complex tasks of distributed access to resources are being solved. About three years ago, shells were created that supported the functions of network search and access to distributed information resources, electronic archives.
The Internet, once used exclusively by research and training groups, whose interests extended right up to access to supercomputers, is becoming increasingly popular in the business world.
Companies are tempted by speed, cheap global communication, convenience for joint work, available programs, a unique database of the Internet. They view the global network as an addition to their own local networks.
With low cost of services (often only a fixed monthly fee for used lines or phone), users can access commercial and non-commercial information services in the US, Canada, Australia and many European countries. In the archives of free Internet access, you can find information on virtually all areas of human activity, from new scientific discoveries to weather forecasts for tomorrow.
In addition, the Internet provides unique opportunities for cheap, reliable and confidential global communication around the world. This is very convenient for companies that have branches all over the world, transnational corporations and management structures. Usually, the use of the Internet infrastructure for international communication is much cheaper than direct computer communication via a satellite channel or through a telephone .
When writing a word with a small letter "Internet" - is the combination of several networks into one. The "Internet" with a capital letter is a global worldwide network.
The Internet (the union of several networks) the owner is the one who organized it for himself. The Internet has no owner, since it is a collection of networks that have different geographical affiliations .
1. The Internet does not have an owner, since it is a collection of networks that have different geographical affiliations.
2. The Internet can not be turned off entirely, because network routers do not have a single external control.
3. The Internet has become the property of all mankind.
4. The Internet has many useful and harmful properties, exploited by stakeholders.
5. The Internet, first of all, a means of open storage and dissemination of information. On the transport route, unencrypted information can be intercepted and read.
6. The Internet can connect each computer to any other connected to the Network, just like a telephone network. If the phone has an answering machine, it is able to distribute the information recorded in it to any caller.
7. Web sites on the Internet disseminate information on the same principle, that is, individually, on the initiative of the reader.
8. Spam servers and "zombie networks" distribute information on the sender's initiative and clog email users' e-mails with spam in the same way that distributors of promotional leaflets and brochures are hammered into real mailboxes.
The dissemination of information on the Internet is of the same nature as rumors in the social environment. If the information is of great interest, it spreads widely and quickly, there is no interest - there is no spread.
Reading information obtained from the Internet or any other computer network, usually refers to the non-public reproduction of the work. For the dissemination of information on the Internet (disclosure), if it is a state or other secret, slander, other information prohibited by law, it is quite possible to take legal responsibility according to the laws of the place where information is entered.
The technology of information retrieval in the Internet
The Internet is growing at a very fast pace, and finding the right information among billions of Web pages and files is becoming more difficult. To search for information, special search servers are used that contain more or less complete and constantly updated information about Web pages, files and other documents stored on tens of millions of Internet servers.
Different search engines can use different mechanisms to search, store and provide information to the user. Search engines of the Internet can be divided into two groups:
• general-purpose search engines;
• specialized search engines.
Modern search engines are often information portals that provide users with not only the ability to search documents on the Internet, but also access to other information resources (news, weather information, exchange rates, interactive geographic maps, etc.).
Search engines of general purpose
Search engines of general purpose are databases containing thematically grouped information about information resources of the World Wide Web. Such search engines allow you to find Web sites or Web pages for keywords in the database or by searching in a hierarchical directory system.
The interface of such general-purpose search engines contains a list of directory partitions and a search field. In the search field, the user can enter keywords to search for a document, and in the catalog select a specific section, which narrows the search field and thus speeds up it.
Filling of databases is carried out with the help of special programs-robots, which periodically "bypass" Web-servers of the Internet. Robot programs read all the documents that are encountered, highlight the keywords in them and put them in a database containing URLs of documents.
Since the information on the Internet is constantly changing (new Web sites and pages are being created, old ones are deleted, their URLs are changed, etc.), search robots do not always manage to track all these changes. The information stored in the database of the search engine can differ from the real state of the Internet, and then the user can obtain the address of an already existing or moved document as a result of the search.
In order to ensure a better match between the content of the search engine database and the actual state of the Internet, most search engines allow the author of a new or moved Web site to enter information into the database by filling out a registration form. In the process of filling in the questionnaire, the developer of the site inserts the URL of the site, its name, a brief description of the content of the site, as well as keywords for which it will be easier to find the site.
Sites in the database are ranked by the number of visits to them per day, week or month. The site's attendance is determined using special counters that can be installed on the site. The counters record each visit to the site and transmit information about the number of visits to the search engine server.
Search for a document in the database of the search system is carried out by entering queries into the search field. A simple query contains one or more keywords that you think are the main keywords for this document. You can also use complex queries that use logical operations, templates, and so on.
Some time after the request is sent, the search engine returns an annotated list of URLs of the documents in which the keywords you specified were found. To view this document in the browser, it's enough to activate the link pointing to the document.
If the keywords were chosen unsuccessfully, then the list of URLs of documents can be too large (it can contain tens or even hundreds of thousands of links). In order to reduce the list, you can enter additional keywords in the search field or use the catalog of the search engine.
The most powerful search engines of general purpose in the Russian-speaking part of the Internet are the servers Rambler (http://www.rambler.ru), Aport (http://www.aport.ru), and Yandex (http://www.yandex.ru). ), and all over the Internet - the Yahoo server (http://www.yahoo.com
We will try with the help of the Russian search server Yandex to find the site "Computer Science and Information Technologies":
1. In the browser, open the start page of the Yandex search server. In the search field enter keywords, for example "computer science textbooks tests CD-ROM".
Spaces between words correspond to the logical operation AND, that is, the search result will be a list of sites on which all the above keywords are present.
2. As a result of the search conducted on November 3, 2001, 118 Web sites containing all of the above keywords were found .
For each document, in addition to the link, the site URL (URL) and its brief annotation are also provided. The site "Informatics and Information Technologies" takes the first place in this list, since it corresponds most to the query. Clicking on the link will load the title page of the site.
In search statistics, you can see the number of sites containing each of the keywords: computer science - 553896, textbooks - 1274027, tests - 2485000, CD-7024321, ROM- 2128526 .
Search in the hierarchical directory system
Web-sites in the database of the search system are grouped into thematic catalogs - analogues of the thematic index in the library. The top-level sections, for example, "Internet", "Computers", "Culture and Art", etc., contain nested directories. For example, the "Internet" directory may contain subdirectories "Providers", "Search", "Communication", etc.
Searching for information in the directory is reduced to selecting a specific directory, after which the user will be presented with a list of links to the URLs of the most visited and important Web sites and Web pages. Each link is usually annotated, that is, contains a short comment to the contents of the document.
We use a hierarchical directory system to find information about Internet providers:
1. Select the section "Computers and communications - Internet access" from the list of directories. You will be presented with a list of links to 1113 most visited sites on this topic .
Specialized search engines
Specialized search engines allow you to search for information in other information "layers" of the Internet: file archive servers, mail servers,
Search for files
To search for files on file archive servers, there are specialized search engines of two types: search engines based on the use of databases and file directories. To search for a file on the system using the database, you just need to enter the file name in the search field and the search engine will output the URLs of the storage locations of this file.
The database of the Russian file search system (http://www.filesearch.ru) contains information on 6 million files located on two thousand file servers of the Russian part of the Internet.
First we search for the file of the interactive ICQ program in the database of the Russian file search system:
1. Open the server in the browser www.filesearch.ru.
In the search field enter the name of the file, for example ICQ. Other fields in the search form allow you to refine the search terms, but they are optional.
2. After a while, the search results appear in the browser window, that is, a list of links to the file archive servers on which this file is stored. By activating one of the links, you connect to the file server and you can start downloading the found file to your computer.
We will first search for the file of the interactive ICQ program in the database of the Russian file search system.
3. To search, for example, the printer driver on the homepage of the search engine, click the Drivers link. Then select the desired printer type in the hierarchical directory tree and activate the link to it.
A list of the URLs of the file archive servers will be displayed, from which the required driver can be downloaded .
Search for email addresses
Specialized search engines allow you to search for an email address by the person's name or, conversely, the name of the person who owns the specific email address. An example of such a system is the WhoWhere search system? (Who is?), Located at: http://www.whowhere.com.