Toggle is a switch that enforces a mutually exclusive state, on or off. It’s often used in forms to replace a submit button when immediate results aren’t necessary or desired. The word is also used to describe an ornamental rod-shaped button that binds to a larger eye or loop in a chain, rope, etc.

When a toggle is activated, users must click it again to disable it, as the current state isn’t retained when clicked. To help avoid confusion, designers typically use colors to indicate active and inactive states (e.g., green as on and red as off). However, these colors can be difficult to differentiate with low contrast, especially for users with color blindness or vision loss. A better approach is to rely on the movement of the switch as well as visual cues, such as positioning and opacity, to communicate its state.

Feature toggles support agile development processes by hiding new features until they’re ready for release, market testing, or another stage in the process. This prevents dev teams from having to commit their newly requested features to a code branch and delay the release of software for months.

For example, an e-commerce company may add a toggle to their configurator that enables experimentation with two different suggestion algorithms and collect user feedback before deciding on which to use in production. They could then create an additional toggle to enable the more effective algorithm once they have data that it’s performing better.