It's so excellent having programs that can just log to stdout, and the main control program (systemd) able to gather all the logs & make them accessible in a unified fashion.
Twenty years ago, two-thirds of the daemons out there had some kind of log to file built in, and everyone needed log rotators, every program logged differently, and trying to see system-wide what happened around a given time was near impossible.
I'm only finally learning journalctl after years of using Linux, and what a lifesaver this would have been if I had only learnt it sooner. This guide is excellent; it is succinct and informative.
Twenty years ago, two-thirds of the daemons out there had some kind of log to file built in, and everyone needed log rotators, every program logged differently, and trying to see system-wide what happened around a given time was near impossible.