daemon

A UNIX program that runs continuously in the background without a visible user interface that performs a system-related service until it is activated by a particular event. Daemons are usually spawned automatically by the system and may either live forever or be regenerated at intervals. This word is often used to refer to programs that handle email. The word daemon is Greek for "an attendant power or spirit."

Gateway Daemon

GateD. Software that supports multiple routing protocols from the GateDaemon Consortium at Cornell University.

name daemon

NameD or named. A UNIX process that converts hostnames to Internet addresses for TCP/IP.