=== The Old Way: init ===

Upon computer boot-up, and after the Kernel process is started, it traditionally launched the '''init''' process (usually PID 1). This important process manages (launches) other common services. The init process also has the ability to manage process (for example, respawing or "restarting" processes if they are terminated for some reason).

Traditionally, the '''init program would run default processes''' that were defined in "shell scripts" contained in appropriate '''run-level''' directory. The run level is a defined state that the Unix/Linux system is currently in (for example, graphical-mode, text-based mode with networking, text-based mode without networking, etc).

=== Why Switch to systemd? ===