Linux.com: An Introduction to Services, Runlevels, and rc.d Scripts

“What’s the first thing that you do once you’ve logged onto
Linux? Is it to manually start up a processes such as Apache or
MySQL, or even start your network connection? Or do you have to
stop applications that have started up without your telling them
to, and which are overloading your machine? If you have unwanted
processes starting at boot time, or find yourself starting
necessary services manually, let’s make your life a little bit
easier by introducing you the world of Linux services.

“A Linux service is an application (or set of applications) that
runs in the background waiting to be used, or carrying out
essential tasks. I’ve already mentioned a couple of typical ones
(Apache and MySQL). You will generally be unaware of services until
you need them…”

Complete
Story