The word “daemon” actually comes from the Greek language, meaning an “inner or attendant spirit” (according to the Oxford American Dictionary).
It is actually a fitting name, like a computer daemon is a continuous running program that does an action trigger only when it receives some input.
For example, a printer daemon sends all information to a printer when a user determines that they have to print a document. A daemon that is running in the mail server routes incoming mail to the appropriate mailboxes.
The Web servers used a “HTTPD” daemon which data that when users delivers access to Web pages to. While daemons were first used in the Unix operating system, they were later incorporated into Mac OS X which is Unix-based.