A background process is a computer process that runs behind the scenes (i.e., in the background) and without user intervention. Typical tasks for these processes include logging, system monitoring, scheduling, and user notification. The background process usually is a child process created by a control process for processing a computing task. After creation, the child process will run on its own, performing the task independent of the control process, freeing the control process of performing that task.

On a Windows system, a background process is either a computer program that does not create a user interface, or a Windows service. The former are started just as any other program is started, e.g., via Start menu. Windows services, on the other hand, are started by Service Control Manager. In Windows Vista and later, they are run in a separate session. There is no limit to how much a system service or background process can use system resources. Indeed, in the Windows Server family of Microsoft operating systems, background processes are expected to be the principal consumers of system resources.

On a Unix or Unix-like system, a background process or job can be further identified as one whose process group ID differs from its terminal group ID (TGID). (The TGID of a process is the process ID of the process group leader that opened the terminal, which is typically the login shell. The TGID identifies the control terminal of the process group.) This type of process is unable to receive keyboard signals from its parent terminal, and typically will not send output to that terminal. This more technical definition does not distinguish between whether or not the process can receive user intervention. Although background processes are typically used for purposes needing few resources, any process can be run in the background, and such a process will behave like any other process, with the exceptions given above.