Processes and systemd

The term systemd refers to one of the most important and controversial pieces of software in Linux. Though if you weren't tuned in to less mainstream Linux distributions, you wouldn't know just how controversial it is. What does systemd do? Well, in a sense, everything.

The D in systemd is for daemon. All a daemon is a process running in the background. Something that silently runs to keep the system going. Systemd is a manager for these daemons, but it also doubles as being process number 1, or the process needed to start the system. Older daemon managers did not have these features, nor did older versions of process number 1 (aka init) have the functionality to do quite literally everything.