In computing, execution is a process by which a computer program is read by a computer and the computer performs the actions encoded in the program. As the processor follows the program instructions, effects are produced in accordance with the semantics of those instructions. The term run is generally synonymous with execute. The act of starting execution is often called launching or invoking in addition to executing and running.

An execution processor comes in many forms. A machine code program may be executed via the programmable interface of a computer where execution involves repeatedly following a fetch–decode–execute cycle for each program instruction executed by the control unit. Source code may be executed by interpreter software. A program may be executed in a batch process without human interaction or a user may type commands in an interactive session.