In computer networks, a proxy server is a server that acts as a go-between for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server. The proxy server evaluates the request according to its filtering rules.

A proxy server has two purposes:

? To keep machines behind an anonymous.

? To speed up access to a resource. It is commonly used to cache web pages from a web server.

A proxy server that passes requests and replies unmodified is usually called a gateway or sometimes tunneling proxy. A proxy server can be placed in the user's local computer or at various points between the user and the destination servers or the Internet.

A proxy that points on WWW traffic is called a "web proxy". The most common use of a web proxy is to serve as a web cache. This is usually used in a corporate environment, though with the increasing use of Linux in small businesses and homes, this function is no longer confined to large corporations. Some web proxies reformat web pages for a specific purpose or audience. A proxy server is a kind of buffer between your computer and the Internet resources you are accessing. They accumulate and save files that are most often requested by thousands of Internet users in a special database, called ?cache?.

Therefore, proxy servers are able to increase the speed of your connection to the Internet. The cache of a proxy server may already contain information you need by the time of your request, making it possible for the proxy to deliver it immediately. The overall increase in performance may be very high. Also, proxy servers can help in cases when some owners of the Internet resources impose some restrictions on users from certain countries or geographical regions.

The Internet is a global network of interconnected computers, enabling users to share information along multiple channels. Typically, a computer that connects to the Internet can access information from a vast array of available servers and other computers by moving information from them to the computer's local memory. The same connection allows that computer to send information to servers on the network; that information is in turn accessed and potentially modified by a variety of other interconnected computers. A majority of widely accessible information on the Internet consists of inter-linked hypertext documents and other resources of the World Wide Web (WWW).

The terms Internet and World Wide Web are often used in every-day speech without much distinction. However, the Internet and the World Wide Web are not one and the same. The Internet is a global data communication system. It is a hardware and software infrastructure that provides connectivity between the computers. The complex communication infrastructure of the Internet consists of its hardware component and a system of software layer that control various aspects of the architecture. While the hardware can often be used to support other software systems, it is the design and the rigorous standardization process of the software architecture that characterizes the Internet.

The movement of information in the Internet is achieved via a system of interconnected computer networks that share data by packet switching using the standardized Internet Protocol Suite (TCP/IP). It is a "network of networks" that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies.

The concept of sending electronic text messages between parties in a way analogous to mailing letters or memos predates the creation of the Internet. Even today it can be important to distinguish between Internet and internal e-mail systems. Internet e-mail may travel and be stored unencrypted on many other networks and machines out of both the sender's and the recipient's control. Today you can send pictures and attach files on e-mail. Most e-mail servers today also feature the ability to send e-mail to multiple e-mail addresses.