Client-server communication models involve a client or clients accessing resources from a server. The client's role is to "ask questions" (start requests), the server's role is to "answer questions" (react on requests). In IP networking, the server typically opens a listening network socket. See netstat to monitor listening sockets.
The word server in day-to-day-use can refer to:
- A computer program, which offers a service, running as a daemon on a computer. Examples include the Apache Web server, FTP server and the Samba SMB server.
- A physical computer ("the server") on which server software runs. AKA: a "server-class" computer.