In Linux and other Unix-like operating systems, the init (initialization) process is the first process executed by the kernel at boot time, which has a process ID (PID) of 1, and is executed in the background until the system is shut down.
The init process starts all other Linux processes, that is, daemons, services, and other background processes; therefore, it is the mother of all other processes on the system.
A process can start many other child processes on the system, but if a parent process dies, init becomes the parent of the orphan process.
Over the years, many init systems have emerged in major Linux distributions, and in this guide, we shall take a look at some of the best init systems you can work with on the Linux operating system.