What is systemd?

systemd is the init system and service manager used by most modern Linux distributions. It starts as PID 1 and manages the entire system lifecycle. Services are defined in unit files (.service) that specify start/stop commands, dependencies, restart behavior, and resource limits. Key commands: systemctl start/stop/restart/enable/status, journalctl for logs. DevOps engineers use systemd to manage custom applications and system services outside of containers.