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Toggle switch, depicted in circuit 'open' position, electrical contacts to left. Background is 1/4" square graph paper.

A toggle switch is a class of electrical switches that uses a mechanical lever, handle or rocking mechanism to actuate them.

Toggle switches are available in many different styles and sizes, and are used in countless applications. Many are designed to provide, e.g., the simultaneous actuation of multiple sets of electrical contacts, or the control of large amounts of electric current or mains voltages.

The word "toggle" is a reference to a kind of mechanism or joint consisting of two arms, which are almost in line with each other, connected with an elbow-like pivot. In the phrase "toggle switch" it specifically refers to one kind of mechanism that can be used to implement a positive "snap-action." However, the word "toggle switch" has come to mean any kind of switch with a short handle and a positive snap-action, whether it actually contains a toggle mechanism or not.

In electronics, the word "toggle" has come to mean circuits that embody an electronic analog of a mechanical snap-action. That is, bistable switching circuits are sometimes called "toggles." In particular, the word can be used for a toggle flip-flop, a circuit in which an impulse causes a transition from whichever state it is in to the alternate state. By further extension, in software, the act of switching from one to the other of two states can be called "toggling."

When used in programs, the term "toggle" is used to indicate turning a feature on, or off, typically by pressing one key to turn the feature on, and then pressing the same key again, to turn the feature off.