Shutdown

Shutdown is the process of powering down a device or system by terminating running processes and, where appropriate, flushing and closing data to ensure a safe and orderly transition from an active to an inactive state.

In computing, a shutdown is typically initiated by the user or administrator through a command or a graphical option. The procedure generally involves notifying applications, synchronizing and closing files, unmounting filesystems, and signaling hardware controllers to cut power. The exact sequence depends on the operating system and hardware platform.

There are two broad types: a graceful (soft) shutdown, which allows programs to terminate cleanly and data to be saved, and a forced (hard) shutdown, which can terminate processes abruptly and increase the risk of data loss or filesystem corruption.

Hardware and firmware commonly support a set of power states under ACPI or similar standards. Examples include S0 (fully on), S3 (sleep or suspend), S4 (hibernation), and S5 (soft off). A full shutdown typically transitions the system to S5, while some devices may perform a power-off without entering a complete state.

Best practices include saving work, allowing ongoing writes to complete, and using scheduled maintenance windows for servers. Abrupt power loss can damage storage devices, disrupt services, and require recovery procedures.

Shutdown is applicable to consumer devices, servers, and embedded systems, and is often part of routine maintenance, energy management, or responses to errors, updates, or power outages.