systemd supervises services (units): it starts them at boot, restarts them per policy and tracks their state. systemctl status httpd, systemctl restart mysql and systemctl is-active exim are the daily bread of server administration.
Unit names differ between distributions (httpd vs apache2, versioned PHP-FPM units), which is exactly the kind of detail good tooling absorbs: probing the right names, reporting per-service up/down, and restarting the correct unit on demand.
Frequently asked questions
What is the difference between restart and reload?
restart stops and starts the service (brief downtime); reload re-reads configuration without dropping connections where supported — prefer reload for config changes.
How do I see why a service failed?
systemctl status name shows the last log lines; journalctl -u name gives the full history.