What is the primary function of the 'init' system in Linux?

The primary function of the 'init' system in Linux is to serve as the first process that the Linux kernel starts during the booting process, which is responsible for managing system run levels. The init process has the process ID (PID) of 1 and is crucial because it sets the groundwork for all other processes in the system. It initializes hardware and system services in the correct order based on the specified run level, which determines what state the system is in and what services should be active.

The init system also takes care of starting and stopping services, managing dependencies, and monitoring the state of these services as the system runs. It ensures that the necessary environment is established for user-level processes to function correctly once the system is up and running. This functionality makes the init system a core component of the Linux operating system, laying the foundations for a stable and organized environment for other services and applications to operate within.