Global computer network Internet. Presentation on the topic: "World Wide Web" Presentation on computer science on the topic global network



Computer network is a set of computers connected by information transmission lines.

The exchange of information through a computer network is called telecommunication.


Types of computer networks

Local

networks

Global network INTERNET

Regional networks

Corporate networks


Local network is small computer network, operating within one premises, one enterprise.

Network topologies

1. Bus topology

All computers are connected to one cable (bus). Terminators are installed at the ends of the cable. The cable used is coaxial cable. Disabling any of the connected devices does not have any effect on the network.

2. Star topology

Each computer is connected by a separate wire to a separate port on a hub (Hub) or switch (Switches).

3. Ring topology

In a ring topology, computers are connected to a cable that forms a ring. Unlike a passive bus topology, each computer amplifies the signals and passes them on to the next computer. Therefore, if one computer fails, the functioning of the network may be disrupted.


Corporate networks are formed to connect computers of certain organizations (military, banking, etc.) that are interested in protecting information from unauthorized access.

A corporate network can connect thousands and tens of thousands of computers located in different cities and countries.

An example is the Microsoft Corporation network – MicroSoft Network (MSN)

Regional networks – connect computers within one region (city, country, continent).

The needs of forming a single world information space led to the creation of the GLOBAL COMPUTER NETWORK INTERNET.

The needs of forming a single world information space led to the creation

GLOBAL COMPUTER NETWORK INTERNET.


Regional computer networks, united

to the global Internet

Regional computer networks united into the global Internet

The reliability of the network is ensured by a large number of high-bandwidth information transmission channels between local, regional and corporate networks.


Internet – is a global computer network in which local, regional and corporate networks interconnected by numerous high-bandwidth information transmission channels

Currently (January 2008), the backbone of the Internet consists of more than 400 million servers.


Internet connection

Every local, regional or corporate network has at least one computer (Internet server) that has a permanent connection to the Internet.

1. Fiber optic communication lines

However, in cases of connecting inconveniently located or remote computer networks, when laying cables is difficult or impossible,

2. Wireless communication lines


If the transmitting and receiving antennas are within line of sight, then use

3. Radio channels

otherwise, information is exchanged via

4. Satellite channel using special antennas

Hundreds of millions of user computers may periodically connect to the Internet through Internet Service Providers. Such a connection can be made either via fiber optic lines or via dial-up telephone channels. Internet providers have high-speed connections from their servers to the Internet and therefore can provide Internet access via telephone channels to hundreds or thousands of users simultaneously.


To connect the user's computer via a telephone channel to the Internet provider's server, modems must be connected to both computers. Modems provide transmission of digital computer data over analog telephone channels at speeds of up to 56 Kbps.

Example of a regular modem

Modern ADSL technologies allow you to use regular telephone channels for high-speed (1 Mbit/s and higher) Internet connections. It is important that at the same time phone number remains free.

Regular and ADSL modems are connected to the USB port of the computer and to the telephone jack.

ADSL modem example


Laptop computer users can connect to the Internet using wireless Wi-Fi technology. Access points are installed at train stations, airports and other public places wireless communication connected to the Internet. Within a radius of 100 meters laptop, equipped with wireless network card, automatically gains Internet access at speeds of up to 54 Mbit/s.

PLC is a new telecommunications technology based on the use of electrical networks for high-speed information exchange(Internet from a socket). In this technology, based on frequency division of a signal, a high-speed data stream is divided into several low-speed ones, each of which is transmitted on a separate frequency, and then combined into one signal.

At the same time, Internet devices can “see” and decode information, although ordinary electrical devices - incandescent lamps, engines, etc. - do not even “know” about the presence of network traffic signals and operate as usual.



Addressing in the Internet


IP address

In order for computers to find each other in the process of exchanging information, there is a one system Usage-based addressing IP addresses.

According to Hartley's formula N=2 I , Where N is the number of possible information messages, and I- the amount of information that the received message carries,

An IP address carries an amount of information I = 32 bits, therefore the total number of possible IP addresses N is equal to:

N=2 I = 2 32 = 4 294 967 296

So, an IP address of 32 bits allows more than 4 billion computers to connect to the Internet.

Every computer connected to the Internet has its own unique 32-bit binary IP address.


Example IP address: 213.171.37.202

For ease of understanding, the binary 32-bit IP address is divided into

There are 4 parts of 8 bits each and each part can be represented in both binary and decimal form.

In decimal notation, an IP address consists of 4 numbers separated by dots, each of which ranges from 0 to 255.

The IP addressing system takes into account the structure of the Internet, i.e. that the Internet is a network of networks, and not a collection of individual computers. An IP address contains the network address and the address of the computer on that network.

Binary

Decimal


To ensure maximum flexibility in the distribution process

IP addresses, depending on the number of computers on the network, addresses are divided into 3 classes A, B, C. The first bits are allocated to identify the class, and the rest are divided into the network address and the computer address.

For example, a Class A network address has only 7 bits for the network address and 24 bits for the computer address, i.e. can only exist N=2 I = 2 7 = 128 networks of this class, but each of which may contain N=2 I = 2 24 = 16 777 216 computers

Binary

Decimal

Class A

Class B

Network address (7bit)

Class C

Network address (14bit)

Computer address (24 bits)

Network address (21bit)

Computer address (16 bits)

Computer address (8bit)


Binary

Decimal

Class A

Class B

Class C

Network address (7bit)

Network address (14bit)

Computer address (24 bits)

Network address (21bit)

Computer address (16 bits)

Network address (8bit)

Whether a computer belongs to a network of one class or another is easily determined by the first number of the computer’s IP address:

  • class A addresses – a number from 0 to 127;
  • Class B addresses – a number from 128 to 191;
  • Class C addresses – a number from 192 to 223;

Question: Determine what type of network our IP address belongs to?


Domain name system

Computers can easily find each other using a numerical IP address, but it is not easy for a person to remember a numerical address, and for the convenience of Internet users, Domain Name System (DNS – Domain Name System).

Domain names and IP addresses are allocated by the International Coordination Center (ICANN).

DNS consists of several words separated by periods. The name structure reflects the hierarchical structure DNS . The domains on the far right are the domains of the first ( top level), to the left - second-level domains, etc.

Example: herba.msu.ru

this address belongs to the computer herba, which is registered in the 2nd level domain msu (Moscow State University) in Russia (ru)/

The Domain Name System assigns a unique domain name to the numerical IP address of a computer.

Computer name (host)


Top level domains are of 2 types:

  • Geographic (two-letter - each country has a two-letter code);
  • Administrative (three-letter)

Level 2 domains are registered by level 1 domain administrators. Thus, Microsoft registered a Microsoft level 2 domain in the top-level administrative domain com. (Microsoft's main server is named www.microsoft.com)

Administrative

Type of organization

a commercial

Geographical

A country

Educational

US Government

International

Germany

US Military

Computer network

former USSR

Non-profit

England/Ireland

When, during business communication, representatives of two companies exchange business cards, then the e-mail address and the name of the company’s corporate Web site will be indicated on them (the business cards). At the same time, you can also hear how the interlocutors exchange “Internet addresses” (“ email addresses") companies. In all of the above cases, one way or another we are talking about the use of domain names.

In an email address, formally, the domain name can be considered what is written after the “@” symbol. For example, in [email protected] The domain name of the mail node is corp.ru.

Attention: You cannot gain any access to the resource by the name itself.

The procedure for using a name is as follows:

1. first by name in hosts file find the IP address,

2. then a connection to a remote information resource is established using the IP address.

Thanks to the domain name system, not only every computer, but also every file on the Internet has its own exact unique address - URL (Universal Resource Locator). It is built as follows:

protocol:// domain name of the computer/ address in the directory tree on the computer/ file name



The Internet, which is a network of networks and unites a huge number of different local, regional and corporate networks, operates and develops through the use of a single principle of routing and data transportation.

Routing and transport of data on the Internet is based on

TCP/IP protocol, which is the basic “law” of the Internet.

The term TCP/IP includes the name of two data transfer protocols:

  • TCP (Transmission Control Protocol) – transport protocol;
  • IP (Internet Protocol) – routing protocol

Internet Protocol (IP) provides routing of IP packets, i.e. delivery of information from the sender’s computer to the recipient’s computer.

sender

Transmission Control Protocol (TCP), those. transport protocol, ensures that files are split into IP packets during transmission and files are assembled during reception


sender. For example: “To: 198.78.213.185”, “From: 193.124.5.33”. The contents of such an “envelope” of information are called Internet package (IP package) and is a set of bytes. IP packets, on the way to the recipient’s computer, pass through numerous intermediate Internet servers, where the routing operation takes place (determining their further path)

DATA ROUTING

In order for the letter to reach its intended destination, the address of the recipient and the address of the sender are indicated on the envelope. Information is transferred between network computers in the same way. Where the IP addresses of the recipient’s computers and

sender

Routing Internet packages (IP packets ) ensures the delivery of information from the sending computer to the receiving computer.


The delivery routes of Internet packets can be completely different, and therefore Internet packets sent first may reach the recipient computer last.

For example:

recipient

sender

The speed of information transfer on the Internet does not depend on the distance of the server

The speed of information transfer on the Internet does not depend on the distance of the Internet server, but on the route of the information, i.e. on the number of intermediate servers and the quality of communication lines (their bandwidth), through which information is transmitted from server to server


DATA TRANSPORTATION

Computers often exchange large files. If such a file is sent in its entirety, it can “clog” this communication channel, i.e. make it unavailable for forwarding other messages.

To prevent this from happening, the sender’s computer must be set to big file into small parts, number them and transform them in the form of separate Internet packets to the recipient computer.

On the recipient computer, it is necessary to assemble the source file from individual parts in the correct order, so the file can only be assembled when all Internet packets have arrived.

Data transport is done by splitting files into Internet packets on the sending computer, individually routing each packet, and assembling the files from the packets in the original order on the receiving computer.


For example:

recipient


2 What is the Internet? InterNet inter – “between” net, network – “network” The Internet is a global network that unites computer networks. Communication channels: cable fiber optic satellite radio communications A provider is a company that provides end users with Internet access through its local network.




4 How did the Internet come about? 1958Creation of ARPA (Advanced Research Project Agency) in the USA e Computer network project ARPANet There is no single center in the network - survivability; when connected new network no modification is required; communication between networks through special nodes - gateways; packet data exchange; 1968 The first network of a new type of 4 computers The network includes 50 universities and laboratories Development of the TCP/IP data exchange protocol First services: TelNet – remote control computer in mode command line FTP ( File Transfer Protocol) – receiving and transmitting files Electronic mail (electronic mail) – messaging


5 How did the Internet come about? 1982 European UNIX network (previously - USA, Canada, England) 1983 The network is divided into two parts: MilNet - for military purposes USA Internet - public network 1984 Domain Name System (DNS) (addresses of the Internet computers Development WWW (World Wide Web) - T. Bernes-Lee, information exchange in the form of hypertext 1991 Russia connected to the Internet The first online stores More than 20 million sites.


6 Internet capabilities (services) WWW (World Wide Web) - hypertext documents Hypertext is text in which each word or phrase can be an active link to another document Hypermedia - documents with active links containing text, pictures, sound, video . Email () FTP (file sharing) Forums (newsgroups, conferences, newsgroups) News subscription Search engines Chats (chat – chat) Personal communication in real time ICQ (I Seek You) – 1-1 conversation, in a group, file sharing Internet phone Skype + speakers + microphone


7 Internet Protocols A protocol is a set of agreements and rules that define how information is exchanged on a computer network. TCP/IP protocol (1974) TCP (Transmission Control Protocol) file is divided into packets of no more than 1.5 KB in size packets are transmitted independently of each other at the destination packets are collected into one file IP (Internet Protocol) determines the best route for packets to travel


8 Internet service protocols HTTP (HyperText Transfer Protocol) - WWW service FTP (File Transfer Protocol) - FTP service SMTP (Simple Mail Transfer Protocol) - send email messages POP3 (Post Office Protocol) - receive email messages (password required) TCP /IP HTTP FTP SMTP POP3 All service protocols are based on TCP/IP! ! !


9 IP addresses IP address: w.x.y.zw.x.y.z network number + computer number in the network Network class w Network number Computer number Number of networks Number of computers A1..126wx.y.z B w.xy.z C w.x.yz Classes D and E are used for official purposes.


10 Domain addresses A domain is a group of computers united according to some characteristic. 1st level domain 2nd level domain 3rd level domain 4th level domain 1st level domains (domain zones) Type of organizationCountry.com commercial organizations.ru Russia.edu education.ua Ukraine.gov US government.by Belarus.mil US military departments.uk UK.org,.net various organizations.it Italy.info information sites.jp Japan.biz business.cn China


11 Address Translation DNS (Domain Name Service) is a domain name service that converts a domain address into an IP address. request DNS server to obtain the site's IP address, wait for a response, request a Web page using the received IP address DNS server DNS server


12 Document address on the Internet URL (Uniform Resource Locator) – the universal address of a document on the Internet. http: // / images/new/ qq.jpg site address directory (folder) name http file: // home page site: index.html, index.htm ftp: // files.vasya.ru / pub / download / qq.zip file on FTP server protocol


13 WWW Service WWW (World Wide Web) is a service for exchanging information in the form of hypertext. Hypertext is text that contains active cross-references to other documents. Hypermedia is a document that includes text, pictures, sounds, video and contains active cross-references to other documents. Browser (browser) – program for viewing Web pages on screen: Mosaic (), University of Illinois, USA Netscape Navigator (from 1995 to 2002) Internet Explorer(versions 6.0, 7.0), included in Windows, 70% Mozilla FireFox(version 2.0), 15% Opera (version 9.0), 15% Details can be found in the next section. in the next section Details can be seen in the next section. in the next section


14 FTP service (file archives) Possibilities downloading files from the server (download) uploading files to the server (upload), including Web sites Access rights login: user code name password: password Anonymous login (automatically in browsers) login: anonymous password: any Search for a file on an FTP server dirinfo, readme, index ftpsearch.com ftp:// user: files.vasya.ru ftp:// files.vasya.ru


15 Distributing programs via FTP freeware – free programs registerware free registration by email shareware (try before you buy) - shareware programs (time limits, annoying messages) demo versions - demonstration of program capabilities (limited functions) beta versions - preliminary (debug) versions of commercial programs, the purpose is to find errors


16 Email () commercial “at” “dog” (Russia) “kitty” (Poland) “rose” (Turkey) 16th century: weight 10 kg, volume 15 l 1972 R. Tomlison SMTP POP3 mail server Mailbox mail server mail server


17 Email message About buying an elephant About buying an elephant To: From: Reply To: CC: Hidden copy(BC): Subject: email title Hello John! Do you have any desire to buy an elephant? Sincerely, Vasily Pupkin, CEO, LLC "Horns and Hooves", St. Petersburg, st. Horn-hoofed, 2 tel. +7 (812) fax +7 (812) greeting main text signature company details attached files (attachments) attached files (attachments)


18 Mail programs Outlook Express– as part of Windows Outlook – as part of Microsoft Office TheBat (Features: creating messages, attaching files, receiving and sending messages, forwarding messages (forward) automatic check mail at a specified interval address book (contact list) sorting messages into folders On many servers you can work with mail through a Web site (Web interface)! ! !


19 Teleconferences, forums Teleconferences (conferences, news groups) are discussions in the form of messaging. Moderator (administrator) – a conference participant who has the right to delete messages for: off-topic (unrelated messages, advertising) insulting participants obscene language FAQ (Frequently Asked Questions) FAQ (Frequently Asked Questions) – a list of the most frequently asked questions newcomers and answers to them. Thread (thread) is a chain of related messages that contains a question, answers and comments. avatar nickname (pseudonym) quote Nick (English nickname) – nickname, pseudonym.


20 Search engines Indexes are robotic programs that constantly scan the Internet and populate databases. Catalogs are databases that are filled in manually by human experts (guides). give out a lot of links 1) some links do not correspond to the topic 2) it is difficult to select the necessary links correspond to the catalog headings, fewer links list.mail.ru, Hybrid systems - index + catalog.


21 Communication in real time (online) Chats (English chat - chatter) exchange text messages real-time Web chats (on Web pages): all have equal rights IRC chats (Internet relay Chat, 1988) “conversation” on channels, there are channel operators with privileges


22 Communication in real time (online) ICQ (English I Seek You), ICQ, Internet pager. Registration: number Features: dialogue discussion in a group file exchange Russian version icq.rambler.ruicq.rambler.ru


23 Internet telephone Skype (real-time conversation Skype PHONE STATION Free Skype calls– Skype File transfer Group and individual chats Teleconferences (up to 9 people) For a fee Calls to landlines and mobile phones Receiving calls from regular phones in Skype Sending and receiving voice messages and SMS


24 Internet via mobile phone WAP (Wireless Application Protocol) downloading toys, music, weather only telecom operator sites, weather sites, email, online stores 1) high cost (old technologies) 2) few capabilities GPRS (General Packet Radio Service) or EDGE (Enhanced Data for Global Evolution) built-in browser (Opera Mini - page compression) support Java language built-in program for can be used instead of a modem for a computer Smartphones: in addition, music playback, video shooting, photo and video operating system, office programs


25 Ethics on the Internet Tolerance: do not suppress the speech of others do not harass or threaten others Ethics of trust: do not distribute the statements, images and opinions of others without their consent do not distort facts, your own and others' opinions do not request or transmit information created by coercion Warn , if the information can be misjudged by a naive person


26 Netiquette Netiquette (net + etiquette) – rules of good manners when communicating on the Internet. Email: subject, greeting, signature do not type sentences in capital letters do not send large files without agreement do not send executable files (*.exe) do not use obscene and slang expressions Forums: read the list of questions and answers (FAQ, FAQ) do not deviate from the forum topic (off-topic) do not type sentences in capital letters do not insult participants Chats: do not interfere in someone else's conversation do not be offended if they leave



  • Except local networks there are also:
  • A corporate network is an association of local networks within one corporation.
  • A regional network is a combination of computers and local networks to solve common problems on a regional scale.
    • The needs of forming a single world information space led to the creation of the global computer network Internet.
  • A global network is an association of computers located at a remote distance for the common use of the world's information resources.
What is the Internet?
  • InterNet
  • inter- "between"
  • net, network- "net"
  • The Internet is a global computer network that unites many local, regional and corporate networks and includes tens of millions of computers.
Organization of global networks
  • When accessing the Internet, we use the services of an Internet provider. The provider connects clients to its network, who become part of the provider’s network and at the same time part of all the interconnected networks that make up the Internet.
Internet addressing.
  • In order for computers to find each other during the exchange of information, there is a unified addressing system on the Internet based on the use of an IP address.
  • Each computer connected to the Internet has its own unique 32-bit (in binary system) IP address.
  • The total number of IP addresses is more than 4 billion:
  • N=232=4294967296
Computer address on the network:
  • The address of a computer on a network is called an IP address.
  • General form:
  • XXX.XXX.XXX.XXX
  • octets
  • octets
  • An IP address consists of four parts, written in dotted decimal notation (for example, 192.168.1.1). Each of these four parts is called an octet. An octet represents eight binary digits (for example, 11000000, or 192 in decimal). Thus, each octet can receive binary
values ​​from 00000000 to 11111111, or 0 to 255 in decimal.
  • The following figure shows an example of an IP address in which the first three octets (192.168.1) are the network number and the fourth octet (16) is the host ID.
  • 195.85.102.14
  • Computer IP address:
  • A host is any computer connected to the Internet, regardless of its purpose.
  • 195th Internet subnet
  • 85th subnet 195 subnet
102nd subnet 85 subnet
  • 14th computer in 102 subnet
  • DNS - Domain Name System
  • Domain Name System (DNS)
  • DNS converts the digital IP address of a host (computer) into a set of characters.
  • The Internet has a more convenient and user-friendly address system, in which the address is indicated by an individual domain name. This is a symbolic naming system.
  • Each domain name consists of several words separated by periods.
  • Domain names are built on a hierarchical principle. The rightmost one is the top-level domain. Next, the domain name is decrypted from right to left.
  • Examples of domain names:
  • microsoft.com is a commercial organization of Microsoft Corporation
  • www.gov.ru – official website of the Russian government
  • A domain is a group of computers united according to some characteristic.
  • www.qqq.microsoft.ru
  • 1st level domain
  • 2nd level domain
3rd level domain
  • 1st level domains (domain zones)
  • Domain names are divided into levels:
  • A first-level (top-level) domain is 2 - 4 letters that are placed at the end of each domain name after a dot (.ru, .com, .ua, .uz, etc.), and are not used for website names by themselves.
  • A second-level domain is obtained by adding the word (site name) before the first-level domain.
  • Examples of public domain zones:
  • .info - information nodes.
  • .net - ensuring the operation of the network
  • .org - non-profit organizations
  • .biz - commercial organizations
  • .com - commercial
  • .gov - government
http://www.myhost.mydomain.spb.ru
  • http:// - hypertext document transfer protocol (Hyper TextTransfer Protocol);
  • www - World Wide Web - World Wide Web;
  • myhost.mydomain - third-level domain;
  • spb - second level domain;
  • Ru is a first level domain.
Routing and transporting data over computer networks
  • Internet packet routing ensures the delivery of information from the sending computer to the receiving computer.
  • Data is transported by splitting files into Internet packets on the sending computer, individually routing each packet, and assembling the files from the packets in the original order on the receiving computer.
Internet protocols
  • For computers to interact with each other on the Internet different types and various OS use various protocols - sets of rules and agreements that describe exactly how data is transferred over the network.
TCP/IP data transfer protocol
  • The Internet operates and develops through the use of a single data transfer protocol, TCP/IP. The term TCP/IP includes the name of two protocols:
  • Transmission Control Protocol (TCP)
  • Internet Protocol (IP)
  • The TCP/IP protocol ensures the transfer of information between computers on a network. In order for the letter to reach its intended destination, the information is packaged in an “envelope” on which the IP addresses of the recipient’s and sender’s computers are “written.” For example, “To:198.78.213.165”, “From: 193.124.5.33”. Contents of the envelope on computer language called an IP packet and is a set of bytes.
  • On the way to the recipient computer, IP packets also pass through numerous intermediate Internet servers where the routing operation is performed. As a result of routing, IP packets are sent from one Internet server to another, gradually approaching the recipient computer. To operate quickly and smoothly, the computers that send, receive, and route packets must follow the same strict rules. The set of these rules for the Internet is the Internet Protocol (IP)
  • There is often a situation on the Internet when you need to send a multi-megabyte file. In such cases, on the sending computer it is necessary to split a large file into small parts, number them and transport them in separate IP packets to the receiving computer. On the recipient computer, it is necessary to assemble the source file from separate parts. All these actions are performed on the basis of Transmission Control Protocol, i.e. the transport protocol.

Description of the presentation by individual slides:

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History of the Internet. The Internet is the World Wide Web, global information space. The history of the emergence and development of this world wide web is bright and unusual, because already 10 years after its appearance it conquered many organizations and countries that began to actively use the network for work. At first, the Internet served exclusively groups of researchers and scientists; soon the military squeezed into this group, and then businessmen. After this, the popularity of the Internet grew rapidly. Users were seduced by the speed of information transfer, cheap global communications, a lot of easy and available programs, unique database, etc. Today, at a low cost of services, every user can access information services from all countries of the world. Also, the Internet today provides global communication opportunities around the world. Naturally, this is convenient for companies that have branches in different parts of the world, for transnational corporations, as well as for management structures.

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How and when did the Internet appear? This happened more than 50 years ago. Back in 1961, on instructions from the US Department of Defense. began work on an experimental project to create a network between computers to transmit data packets. Each node has the authority to originate, transmit, and receive messages from other computers. In this case, messages are divided into standardized elements called “packets”. Each package is assigned an address, ensuring correct and complete delivery of documents. In the first version of the theoretical development about the predecessor of modern world wide web, published in 1964 by Paul Baran, argued that all nodes on a network should have the same status. This network was called ARPANET, and it was intended to explore various options for ensuring reliable communication between different computers. It became the immediate predecessor of the Internet. -Paul Baran - thanks to whom the network appeared in 1964 - the progenitor of the modern Internet.

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For eight years, DARPA worked on the project and in 1969, the Department of Defense approved ARPANET as the leading organization for research in the field of computer networks. From this time on, nodes of the new network began to be created. The following year, ARPANET hosts used NCP for communication. A year later, there were already 15 nodes in the network. 1972 is the year in which addressing development groups were created to harmonize different protocols. At the same time, TCP/IP data transfer protocols were developed. The first ones were made in 1973 international connections. The countries that joined the ARPANET network were England and Norway. The ARPANET project was so successful that soon many organizations in the USA, England and Norway wished to join it. The history of the Internet is just beginning here. In 1976, the UUCP protocol was developed, and three years later they launched USENET, which runs on UUCP. The US Department of Defense declared TCP/IP its standard in 1983. 1984 was the year the DNS system was introduced, and total number hosts exceeded 1000. The formation of CSNET accelerated significantly in 1986, when they began to create supercomputer centers. By 1987, the number of hosts had exceeded 10 thousand. And in 1988, NSFNET began using the T1 channel. -DISA - Defense Information Systems Agency - defense information systems agency.

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Internet in Russia. The network came into operation in 1995. In 1996-98, a backbone network for science and higher education was built. At the same time, networks of commercial suppliers emerged and developed. At first they focused on connecting organizations. In 1998, Rostelecom, together with Relcom, formed the company Relcom - DS. Today it is the largest Internet service provider in Russia. Today on the Internet there is already huge base information in Russian. According to sociologists, at the end of 1998, about 1.5 million people in Russia were Internet users, and more than half of these users lived outside of Moscow. In 1999, the number of users exceeded 5 million people.

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Negative influence of the Internet on humans. -Internet and vision. -Computer and poor health. -The Internet is an addiction.

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1.1Internet and vision. In fact, it is not the Internet that has a bad effect on vision, but the computer, but the Internet is definitely to blame for this. Let's look at the statistics of whose vision deteriorates more. This means that those users who communicate on the computer are more likely to worsen their vision. Such users communicate using the Internet, which means the Internet negatively affects our vision. Vision deteriorates due to greater fatigue, when a person sits at the computer for a very long time and continuously, vision weakens. Vision also deteriorates when reading from a monitor screen. 1.2Computer and poor health. A person working at a computer for a long time must maintain a relatively motionless position, which negatively affects the spine and blood circulation throughout the body (blood stagnation). Long-term use of the keyboard leads to overstrain of the joints of the hand and forearm muscles. Working at a computer involves processing a large amount of information and constant concentration of attention, therefore, when working at a computer for a long time, mental fatigue and impaired attention often develop. Working at a computer often absorbs all the attention of a working person and therefore such people often neglect normal nutrition and work from hand to mouth all day. This is directly related to the Internet, because a person will spend more time at the computer only when he is on the Internet, the person will be absorbed a large number of information, communication, and he will lose track of time, and his health will deteriorate every minute. 1.3The Internet is an addiction. Computer addiction is no less dangerous than drug addiction, as it leads to a significant disruption of adaptation in society (inability to work, inability to start a family or simply take care of oneself). Internet addiction is a mental disorder, an obsessive desire to connect to the Internet and a painful inability to disconnect from the Internet in time.

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Positive influence of the Internet on people. Positive features of the influence of the Internet on a person - Earning money online, finding a job. - Possibility of paying and ordering many services via the Internet. - Show yourself, show yourself to the world. - Talk to people, find old friends, classmates. - On the Internet you can always get the latest news on any topic.

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We have looked at some of the negative aspects of the Internet, but you can also find positive ones. We can communicate with people who are thousands of kilometers away from you, we can exchange information at a distance, we can make all kinds of purchases without leaving home, etc. Let's consider useful features Internet. 2.1 Online purchases. Nowadays, shopping through online stores is becoming very popular; you choose the product you need, put it in the online shopping cart and pay using a card, ATM or web wallet. It is very comfortable. 2.2Internet money. Now at this time it has become popular to have an online wallet. This is a kind of wallet, but we cannot see or touch it because... it is in an interactive space. It is visual, but the money it contains is a real means of payment. With this money we can pay for other goods from online stores. And these are just the main advantages. The needs and requests of Internet users are very different. Some want to get something new software. Others are looking for certain documents they need to professional activity. Still others connect to the network to receive email. The Internet helps everyone.

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