Internet as a global information system. When did the Internet appear in Russia? Internet resources

What is email?

E-mail is in many ways similar to regular postal mail. Having written a letter on a piece of paper, the sender places the sheet in an envelope, seals it, sticks a stamp and writes the recipient's address. He then places the envelope in the nearest mailbox. After some time, the letter will be delivered to the recipient. If it turns out that for any reason the letter cannot be delivered, it will be returned to the sender. �Email does the same thing much faster with the help of the Internet and computers, so it is mainly used these days for daily business and personal correspondence.� Instead of paper and pen, you use a keyboard to type the text of the letter into an email program or browser window. You send letters by clicking the “Send” button or similar. � Mail servers act as post offices, and Internet channels serve as postmen. Mail servers store users' electronic mailboxes. As soon as the user looks into his mailbox, he will immediately see incoming letters. From there, it's a matter of minutes (or seconds) to read them.�What is a letter sent via email?�You can think of email messages as electronic documents, similar to documents created by programs such as Microsoft Word, Excel, WordPad or Notebook.

Typically, special email programs are used to create, send and receive email messages, such as Microsoft Outlook Express, Netscape Composer, The Bat! etc. Another popular way of working with mail does not involve using a special mail program - a regular browser is enough. A visitor just needs to go to the mail page to send and receive letters. In addition to plain text, audio messages, images, office documents, in short, everything that can be recorded in a file are sent via email.

What is an email address?

An electronic mail address, or e-mail address, is a name that uniquely identifies the electronic mailbox to which an e-mail message is sent. Different types of networks may have different email address formats. The following type of address is accepted on the Internet: user_name @domain_name. Usually the username coincides with the login by which he accesses the Internet from his provider

What is e-mail?

E-mail is a letter sent using a computer (electronic mail). The content of the message can be either text entered from the keyboard or a file stored on disk. The sent message is stored in a “box” on the mail server that serves the recipient’s email address until he downloads the message to his computer. After reading, the message is deleted from the mail server and can be saved, printed, forwarded to another recipient, or deleted by the user.

What is login and password?

Login (from English log in) is a set of letters and numbers necessary for authorization and identification of you in the system. The login is used in conjunction with a password and only you should know them.

Basic rules when creating a password:

1. Don't use the most common password options.

2. Do not use passwords similar to your login.

3. Use large and small letters, as well as numbers in your password (except for date of birth, phone number, etc.)

4. Try to come up with a password that you can remember in a year.

5.The longer the password, the safer it is.

What free mailboxes are there?

Currently, there are quite a large number of servers that provide free mailboxes. Here are some of them:�Mail.ru�Chat.ru;�Yahoo.com;�Hotmail.com

Before we begin the practical part, let's do some eye exercises (exercises are performed)

Practical part

Find the registration button. Fill in the fields of the registration window.

Reinforce the concepts of “login”, “password”, “@”. Mailing addresses.

Create and enter your username and password. After successful registration, close the window and log in to your email inbox again.

We get acquainted with the command buttons of the program: view mail, write, send, attach a file, etc. We write a letter to each other using the created email addresses, for this the teacher suggests exchanging email addresses. We accept mail - open the letter. Attach a postcard. Individual tasks: Angelica writes an invitation to Ulyana’s birthday, Kirill invites Nikita, Kostya writes a congratulation on March 8th (to a girl of her choice). Angelina writes a request to a classmate for help with her homework, etc. The teacher approaches students who are having difficulties and observes the work in the class. The teacher explains the concept of email culture.

The teacher asks those who were unable to create their own mailbox to raise their hands. The teacher asks those children who have already sent a letter to raise their hands. (students should all see the phrase “the letter was sent successfully”) The teacher asks those children who have already received the letter by e-mail to raise their hands. The teacher verbally encourages the children who completed the task the fastest. The teacher invites those children who have completed the task to send each other the text file that they created at the beginning of the lesson. At this time, the teacher works with those children who have difficulties.

“The Internet is a global information system that

· logically interconnected by a space of globally unique addresses based on the Internet Protocol (IP) or subsequent extensions or successors to IP;

· capable of supporting communications using the TCP/IP family or its subsequent extensions/successors and/or other IP-compatible protocols;

· provides, uses or makes available on a public or private basis high-level services built on top of communications and other related infrastructure.”

The Internet is based on a system of so-called IP addresses. Each computer has a unique network number ( IP address), occupying 4 bytes. It is usually written as four decimal numbers in the range from 0 to 255, separated by dots. For example, the address is 212.192.96.101. At the international level, IP addresses are distributed by a specially authorized organization, the Internet Network Information Center.

A digital addressing scheme is necessary for computers, but it is inconvenient for humans. Therefore, in 1983, immediately after the ARPAnet switched to the IP protocol, a system for naming computers with meaningful names was proposed: all names on the global network are divided into groups (domains) nested within each other. An online domain name consists of several (derived from American postal customs) names separated by dots.

First-level domain names are fixed by international agreements. They are divided into two classes - functional and geographical.

Functional domains are designated by three letters; there were only six of them in the original version of the standard:

· edu – educational organizations;

· com – commercial organizations;

· net – network service providers;

· mil – military organizations;

· gov – government agencies;

· org – other non-profit organizations.

Geographic first-level domains are two-letter, for example

· su – Soviet Union;

· ru – Russia;

· us – USA (United State);

· uk – Great Britain (United Kingdom);

Administrators of second-level domains register names of third-level domains, etc. The mapping of domain names to IP addresses (address resolution) occurs automatically; this is done by a special network service - Domain Name Service (DNS), which works using the appropriate auxiliary protocols.

The second paragraph of the definition reveals the content of the transport layer on the Internet, which necessarily uses the TCP/IP protocol family. In this family, IP, along with some other supporting protocols, is responsible for the transmission of a single packet, where delivery of the packet is not guaranteed, but TCP (Transfer Control Protocol) is responsible for the proper delivery of the entire message. To do this, the sender's message is divided into separate packets, which are delivered over the IP protocol, and the recipient is reassembled and situations where individual packets are lost or arrive in the wrong order in which they were sent are corrected. Thus, the TCP/IP protocol stack provides the upper layer with a comprehensive service for establishing a reliable virtual connection between any two processes operating in different locations on a global computer network.

According to the third point of the definition, the Internet should be understood not only as a global message transportation network, but also as a system for providing high-level services (e-mail, World Wide Web, etc.) built on top of it and which belong to a higher application layer.

Internet as a global information system

Prepared by: teacher of mathematics and computer science

Municipal educational institution "Uysko-Chebarkul secondary school"

Musienko Vera Petrovna

Any service on the Internet is provided using server programs. Servers are divided into several types, depending on the type of service that is provided to users: - web servers (provide access to information in the form of web pages); - file servers (provide access to files) ; - mail servers (exchange email messages) ; - game servers (used for simultaneous play by several users) and etc.

Internet services built on client-server technology Communication Information -Email - File Transfer (FTP) - Video conferencing - WWW - World Wide Web - Direct communication forums (chat) - IP telephony (Internet telephony)

Email - e-mail.

• Email- the most popular type of service on the Internet. Its purpose is to support the exchange of emails between users. To create and receive letters, a variety of programs for working with e-mail are used - specialized ones, for example Eudora, or built into a Web browser, for example Netscape Navigator.

Email operation scheme

Network node

User's computer

Email server

Client e-mail.

Communication session

POP3 protocol

SMTP protocol

Client mailbox. Address: name@server_address

Mail folders:

• Inbox
• Outgoing
• Sent

INTERNET

Video conference

Video conference- a field of information technology that simultaneously provides two-way transmission, processing, transformation and presentation of interactive information at a distance in real time using computer hardware and software.

Conferences

symmetrical asymmetrical

(subscribers see and hear each other) (some participants only see and hear, but

do not participate constantly).

Instant messaging services (chat).

Instant Messaging Service is a method of transmitting messages to interactive users over TCP/IP (network service). The contact list displays connected users who can participate in the conversation.

The most common instant messaging program.

ICQ (I Seek You - I'm Looking for You) is a popular program (the most common Internet pager) for communication in real time. Since ICQ is an outdated centralized network with a closed protocol, experts currently recommend that users switch from the ICQ system to Jabber.

IP telephony (Internet telephony)

IP telephony is a system that allows you to conduct a conversation in real time using Internet communication channels.

There are two types of connection, depending on the communication devices used.

First option, computer - computer;

Second option, computer-phone.

File transfer (FTP)

File transfer (FTP) is a system for transmitting electronic information that allows each network user to access programs and documents stored on a remote computer.

WWW - World Wide Web

The World Wide Web(English) World Wide Web) is a distributed system that provides access to interconnected documents located on different computers connected to the Internet.

Email – e-mail Network node Server e-mail Protocol POP3 Client mailbox. Address: pa User's computer e-mail client (Outlook Express) SMTP protocol Mail folders: Inbox Outbox Sent INTERNET

Teleconferences - Organization of mail correspondence. To become a participant in the conference, you need to subscribe to it. There are specific addresses for these purposes. A teleconference is always devoted to a specific topic, so correspondence in it occurs only within the framework of the topic.

Direct communication forums – chat Literally translated, “chat” in real time (chat conferences). Communication between participants takes place online in written form. Just like in a teleconference, chat conference participants are divided into thematic groups.

Internet - telephony, voice communication via the Internet in online mode. This is a new, developing service. Its main advantage over the telephone is its low price. The quality is still inferior to telephone communications (time delays, sound distortion), but there is no doubt that over time this drawback will be overcome.

File transfer This service is often called by the name of the protocol used: FTP (File Transfer Protocol). On the Network side, the service is provided by FTP servers, and on the user side by FTP clients. The purpose of the FTP server is to store a set of files for a wide variety of purposes (usually in archived form).

The World Wide Web (WWW, World Wide Web) is the most popular information service on the Internet today. This is a huge information system distributed throughout the world, containing millions of documents on a wide variety of topics. This service operates based on the HTTP protocol.

Questions: 1. Explain the difference between communication and information services on the Web. 2. Why do the email server and client use different protocols? 3.What is the difference between a chat conference and a teleconference? 4. What is the advantage of Internet telephony compared to traditional telephone communication?