systemd is a system and service manager for Linux operating systems. It is designed to start, stop, and manage system processes and services during boot-up and while the system is running. By using units, which are configuration files that define services, sockets, devices, and more, systemd streamlines the management of system resources. One of the key features of systemd is its parallel service startup, which allows multiple services to launch simultaneously, improving boot times. Additionally, it provides tools for logging and monitoring services, making it easier for administrators to manage system performance and troubleshoot issues.