They are the processes which run in the background and are not interactive. They have no controlling terminal.
A daemon is a background, non-interactive program. It is detached from the keyboard and display of any interactive user. The word daemon for denoting a background program is from the Unix culture; it is not universal.
Daemon stands for Disk and Execution Monitor. A daemon is a long-running background process that answers requests for services.
- init: Takes over the basic running of the system when the kernel has finished the boot process.
- inetd: Responsible for starting network services that do not have their own stand-alone daemons. For example, inetd usually takes care of incoming rlogin, telnet, and ftp connections.
- cron: Responsible for running repetitive tasks on a regular schedule.