A lot of users of the Internet often confuse server with router. These devices are very similar, but not the same. Router can be a server and of course, server can be a router, but both are used different. We deal with server, when we want to take advantage of NIS (e.g. mail, ftp or www). Customary, we can say that server is a program providing services for other programs (usually run on other computers in the network). Server is often a computer which provides such services, that usually means sharing some resources with other computers or mediating in the transfer of data between computers. Server is also called software systems that is involved in the provision of resources. Examples of shared resources are files, databases, web links, as well as peripheral devices such as printers or scanners. The server can be a regular computer. In order to fully exploit the opportunities offered by the server software, it should be a machine designed for this role. Such machines are designed for continuous operation. They are equipped with large and fast hard drives (mostly SCSI), large amount of RAM with ECC and the most efficient server processors. Most server motherboards support 2, 4 or more processors. The server have to be reliable machine for this purpose, therefore it often has 2 or more built-in hot-plug power supply and emergency power supply. Also the room in which it stands should have adequate ventilation or air conditioning. Resource sharing is performed on a client-server. It can also be done on the basis of Peer-to-peer network. Servers usually work under operating systems such as FreeBSD, GNU / Linux, Solaris, Novell NetWare, HP / UX, Microsoft Windows Server 2003, 2008, or 2012. With the server, you can publish a website, use e-mail or store files. Several dozen programs that provide services can be run on the server. Typically, each such online computer specialist in different task. One is responsible for displaying web pages, another for handling e-mail, another for backup.