Pronounced “demon.” A Unix program that executes in the background, ready to perform an operation when required. Functioning like an extension to the operating system, a daemon is usually an unattended process that is initiated at startup. Typical daemons are print spoolers, e-mail handlers, or a scheduler that starts another process at a designated time. The term comes from Greek mythology meaning “guardian spirit.”
In the Windows NT environment, a service is analogous to a daemon.