Global Network Wide Area Networks (WAN), which belong to a regional computer networks, designed as LAN to provide services, but much larger number of users located over a large area.

Because of the long channels of communication to build is very expensive, so the global network most often created by large telecommunications companies to provide paid services to subscribers. Such networks are called the social or public. But in some cases created as a private WAN networks in major corporations.

Subscribers can be LAN WAN enterprises that are geographically distant from each other, which need to share information among themselves. In addition, individual computers can use the services for WAN access, as to corporate data, and to public data Internet.

Companies that support the operation of the network, called network operators and companies that provide paid services to subscribers are called service providers or service providers.

In global networks for information transmission, the following types of switching:

circuit switching (used when sending audio over ordinary telephone lines; ATM – is a communication technology that combines the principles of packet switching and channel for communication of various types);
message switching (used mainly for sending e-mail, teleconferences, e-news);
packet switching (data transmission, recently also used for audio – and video).

Of great interest is the global information network Internet. Internet brings together many different computer networks (local, corporate, global), and individual computers that are sharing information via the public telecommunications.

Virtually all Internet services built on the principle of client-server. All information is stored on Internet servers. Exchange of information between servers on the network is carried on high-speed communication channels or routes.

These routes include: dedicated analog and digital telephone lines, optical communication channels and radio, including satellite communication lines. Servers, combined with high-speed highways, constitute a basic part of the Internet.

Individual users connect to the network through computers local Internet service providers, Internet – ISPs (Internet Service Provider – ISP), which have a permanent connection to the Internet. Regional provider connects to a larger provider on a national scale, which has sites in various cities.

Network of national providers together in a network of transnational providers or providers of the first level. Combined network providers are the first level of the global network of Internet

Services that may be provided to users on the Internet:
E-mail E-mail;
computer telephony
File Transfer FTP;
terminal access for interactive work on a remote computer TELNET;
Global System for teleconferencing USENET;
reference services;
access to information resources and search tools on the Internet.