This encyclopedia entry provides a detailed introduction to the Cron system, the basic Linux tool for automating scheduled tasks. The description covers the structure of Cron, including the role of the background daemon and the crontab files containing the tasks. We will get acquainted with the Unix roots of the system and the development of modern implementations. The article places great emphasis on a detailed description of the crontab syntax, introducing the use of timing fields, special characters, and user-friendly aliases such as @daily. We distinguish between user-level and system-level cron job management, covering the use of the /etc/crontab and /etc/cron.d directories. The description also provides practical advice on avoiding the most common pitfalls, such as problems with the PATH environment variable and the correct handling of command output. Finally, we will introduce the role of Anacron, which ensures reliable execution of tasks on machines that are not constantly running.