[ghostpepper]

Is there a good overview of these pieces and what they're responsible for and how they fit together?

I had a quick skim of the docs on systemd.io and there are quite a few documents but they don't seem particularly organized and I couldn't see a good architecture overview.

[mattpallissard]

I hate to be this guy but the man pages have it all

  man -k systemd

There's some terminology to learn, but overall it's pretty approachable.

Edit; and as far as architecture goes they are all _separate_ programs. It's not a single large "systemd"