"A Server is a computer, or a software application that provides a specific kind of service to client software running on other computers. The term can refer to a particular piece of software, such as a Web Server, or to the computer on which the software is running. A single computer may have several different server software applications running on it, thus providing many different servers to clients on a network."

I guess, basically, a server is what you need if you want to host other people too... For your friend, I think you just need a webhost...