What is the init process?

The init process (or systemd in modern distributions, or SysVinit in older ones) is the first process started by the Linux kernel after booting. Its PID is always 1. It is responsible for system initialization, starting other services and daemons, managing processes, and shutting down. Systemd, as a modern implementation, performs these functions in parallel, speeding up the boot process, and provides extended capabilities for managing services, logging, and other system aspects.