The electronic computer network (or simply computer network) is a joint connection of several separate computers to a uniform data link.
The basic purpose of the computer network consists in sharing of resources and implementation of fast communication both in the organization, and beyond its limits.
Let's consider the main concepts which are used in computer networks.
The client – the computer connected to the computer network.
The server (server) – the computer providing the resources to clients of a network. Distinguish the following types of servers:
- the file server is intended for storage and providing files with which users work;
- the server of databases provides access to clients to the general databases;
- the application server serves for granting to users of applied programs;
- the print server provides the press on the general printing device from all workplaces;
- The web server provides providing information through the Internet network;
- the e-mail server provides e-mail circulation, both in the organization, and in an external network.
Resources – disks, files, printers, modems and other elements used during the work in a network.
Depending on the size all electronic computer networks share on:
- The Local Computer Networks (LCN) which subscribers are concentrated on distance of 10 - 15 km. Such networks unite the computers placed in one building or in several nearby located buildings.
- The regional networks, which subscribers are concentrated on distance of 10 - 100 km. Regional, city and regional networks belong to such networks.
- The global networks concentrated on distance of 1000 and more kilometers. The networks uniting the cities, areas, areas, the countries belong to such networks. The most known among them - Internet, Fido, Sprint, Relcom.
In many organizations in which personal computers are operated, local computer networks are created. It becomes because a LAN is provided by a number of considerable advantages, in comparison with use of separate computers. Let's consider these advantages.
Division of resources – allows to use economically resources in information system. For example, to make the press from all computers on one printer, to use one DVD disk drive, etc.
Division of data – allows to have access from different workplaces to files which are located on other computers. Thanks to division of data it is possible to organize work of several users on creation of the general document.
Division of software - allows users to use the programs installed on other computers.