Tuesday, April 2, 2013

Main systems and concepts of the Internet network

The worldwide network Internet consists of several systems which can function both together, and independently from each other. Let's consider in detail these systems.

World Wide Web (WWW - is literally translated as a world wide web) is a global hypertext system of the documents connected by electronic links.

WWW allows to move between various documents, using hyperlinks, and a geographical arrangement of computers on which information is stored, has no value.

The hyperlink is an electronic link in the document, connecting it with other document.

For viewing of hypertext documents special programs – browsers are used. The browser is an intellectual program which itself defines a type of the looked-through hypertext. Therefore depending on various conditions the same hypertext document in the browser can look differently.

E-mail (E-mail) - system of electronic messages between computers.

During the work with e-mail each subscriber has to have the unique postal address, for example, master@primer.ru. Record of the postal address consists of the following elements:

master - a name of the subscriber;
@ - determinant of the postal address in Internet;
primer.ru - a name of the server on which "mailbox" of the user settles down.

FTP (File Transfer Protocol - the file transfer protocol) – the system, allowing to copy on the computer files from any other computer connected to Internet. FTP servers represent as though the catalogs containing thousands files with various information, including programs, sound files, drawings, video images, etc.

TCP/IP (Transmission Control Protocol/Internet Protocol - the protocol of management / the Gateway protocol) - provides with transfer delivery to the address, so-called, network packages.

The sense of a network package consists that any message transferred on the Internet networks, shares on packages, i.e. on some separate messages. Then these packages are transferred on a network to the necessary addressee. And each package can be transferred on the own way which isn't coinciding with ways of other packages. In a terminal point of appointment these packages gather in the initial message. If any package was lost on the road, there is a repeated transfer of this package, instead of entirely all message.

The described action is called as package switching in a network. Thanks to package switching high reliability of functioning of the Internet network is reached. As if on any information highway there will be a failure or its failure, the sent packages all the same will achieve the object. They will simply bypass faulty sites of a network on other way.

HTTP (HyperText Transport Protocol) – the protocol of transfer of the hypertext. Defines a way of transfer of hypertext pages in a world wide web from the server to the browser to the browser.

IP Address – the address by which the computer in the Internet network is identified. Usually registers as four numbers, divided by points, for example, This number can constantly is registered at the computer, or automatically to be appropriated each time, at connection to Internet. For example, servers of the large organizations have the permanent address in Internet. If the computer is connected to Internet by means of the telephone line and the modem, as a rule, each time at connection is appropriated to it the new address.

DNS (Domain Name System) is a system of domain names which represents the set of the tables displaying numerical IP addresses of computers in a clear look for the user distributed on Internet. In other words, DNS will transform the numerical address of the computer to a text form (or the name is simple). For example, the address of a look in system of domain names can be displayed as inf1.info

In Internet there are special programs - servers of names (name servers) which contain in a form of tables numerical IP addresses of computers, symbolical addresses and additional information. When the user specifies the text address of the interesting computer, this information arrives on the server of names. The server will transform a computer name to the numerical IP address. And then there is a computer search in a network to its IP address.

URL (Uniform Resource Location - the uniform index of resources) - provides the uniform description of placement of resources in Internet.

The general view of the address of a resource in a network looks as follows:

report://server/way / file_name

HTML (HyperText Mark-Up Language - a hypertext markup language) is a formatting language which describes how the page with the hypertext will look, at its viewing in the browser. The HTML document represents the text for which special codes - tags are specified. These codes define how the document in a browser window has to look. When the browser opens the HTML document (i.e. the document in the form of the hypertext), he "reads" tags. And depending on tags the browser submits the document as it looks on the screen.

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