Daemon (computing)

In computing, a daemon ( DEE-mən or DAY-mən) is a program that runs as a background process, rather than being under the direct control of an interactive user. Customary convention is to name a daemon process with the letter d as a suffix to indicate that it's a daemon. For example, syslogd is a daemon that implements system logging facility, and sshd is a daemon that serves incoming SSH connections. Even though the concept can apply to many computing systems, the term daemon is used almost exclusively in the context of Unix-based systems. In other contexts, different terms are used for the same concept. Systems often start daemons at boot time that will respond to network requests, hardware activity, or other programs by performing some task. Daemons such as cron may also perform defined tasks at scheduled times.