The word operation can mean any of several things:

• The method, act, process, or effect of using a device or system. See military operations, manufacturing operations, anomalous operation.
• In medicine, a surgical procedure to diagnose, cure or palliate a certain disease.
• In mathematics, an action (often represented by an operator symbol) applied to numbers or other entities to produce a well-defined result. Examples include addition, multiplication, root extraction, and comparison. See unary operation, binary operation.
• In computer programming, a program step, usually specified by a part of an instruction word, that is undertaken or executed by a computer. Logical operations such as And, Or and Not are also operations typically performed by devices known as logic gates.
• In music a basic operation is one which may be performed on a set of pitches or pitch classes, including transposition, inversion, and multiplication. These may be combined to form compound operations, and inversion may be more accurately thought of as the compound operation transpositional inversion. See: transformation, permutation, counterpoint.
• The tactical shooting PC game Operation Flashpoint.
• The game of physical skill, Operation.