server is a logical concept. in plain words, one networked computer providing certain services and access for other computers (client) is a server. except for diskless computer, any computer with a hard driver and network card can be used as server. there are many kinds of server, file server, web server, application server... what kind of server you are talking about? generally, a server is used for a specific purpose, in comparison to a desktop its user appllications can be significantly less.