A daemon is a long-running background process that answers requests for services. The term originated with Unix, but most operating systems use daemons in some form or another. In Unix, the names of daemons conventionally end in “d”. Some examples include inetd , httpd , nfsd , sshd , named , and lpd .

What is daemon used for?

A daemon (pronounced DEE-muhn) is a program that runs continuously and exists for the purpose of handling periodic service requests that a computer system expects to receive. The daemon program forwards the requests to other programs (or processes) as appropriate.

Why is it called a daemon in Linux?

The term was coined by the programmers of MIT’s Project MAC. They took the name from Maxwell’s demon, an imaginary being from a thought experiment that constantly works in the background, sorting molecules. Unix systems inherited this terminology.