(1) A computer that acts as a source of information or signals. The term can refer to any computer, from a centralized mainframe to a server to a client PC (user's machine). In a network, clients and servers are hosts because they are both sources of information in contrast to network devices, such as routers and switches, which are responsible only for directing traffic. See host adapter and host name.

(2) To have in one's possession. When you "host a computer system," the system is running in your facility. It is technically accurate to say that "the company hosts many hosts," but such usage would only sound strange.