which processes writes to journald ?

[Nishant Nayan <nayan.nishant2000@xxxxxxxxx>]

Does journald logs only for systemd services or for any process?

I am kinda confused about difference between systemd units and userspace processes, are both same ?

Do we have any classification so as to which process will send logs into which socket?

For example :-

Which processes sends logs into 

1) /dev/log 

2) /run/systemd/journal/stdout 

3) /run/systemd/journal/socket ?

Nishant