What is systemd?

Systemd is a system and service manager. The name is short for ‘system daemon’, an ongoing service that manages the system. As it is also a service manager, it is responsible for start, stopping, and monitoring services. Systemd replaces the SysV init system and focuses on performance and resource management. It was created by Lennart Poettering in 2010, with Fedora Linux being the first to adopt it in May 2011. In 2015, several major Linux distributions started shipping with systemd.

If you are running a modern Linux distribution, changes are high that systemd is being used. This can be confirmed by using a command like systemctl on the command-line.

Systemd units

An important part of systemd are its unit files. These files define how components interact with each other, including the definition of a service or a mount point.