I could turn my mac into an FTP server, a file sharing server and a music sharing server. From where I am standing, this doesn't look like it's an actual server; or is it? A server to me is a "box" with no screen, and sits on a shelf, generally doesn't turn off
closed as off topic by Ben Pilbrow, Tom O'Connor, SvW, Iain♦, John Gardeniers Apr 14 '11 at 11:22
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The term "server" refers to the functionality, not the shape or position of the box. Windows servers often have attached screens with full guis (however silly of them); some servers live on desks in lobbies instead of in climate controlled racks; and last but not least some servers even turn off now and then!
The line gets drawn when other computers depend on network access to a "central" one for services of any kind. That box becomes a server.