This portal talks about process management. Technical language could be used.
In any Debian system, there are a number of processes that run in the background so that certain system tasks can be performed. For example, Cron is such a process. It runs in the background every minute and executes any command that has been scheduled to run at that time.
Other processes including things like web servers, ftp servers, print spoolers, etc. Just because you cannot see the program running on your screen doesn't mean that it isn't running and isn't keeping order in the universe.