A toggle is a pin passed through the eye of a rope or a hook to fasten it. The word also refers to a software feature that enables back and forth switching between different settings, programs or options. In computer technology a toggle is used to turn functions on and off, like the key that turns Caps Lock on and off.

The use of a toggle is appropriate for features that are transitionary and short-lived — typically no more than a week or two, although product-centric toggles may need to stay in place for longer. The toggling decision for a Release Toggle should not stick around much longer than the duration of a particular release cycle.

Savvy teams view Feature Toggles as inventory that comes with a carrying cost and seek to minimize the number of toggles in the codebase. This is why many teams adopt a policy of adding a task to the backlog for removing a Release Toggle once it has completed its transitionary lifespan and why other teams employ “expiration dates” on their toggles which will trigger a failure of a test run (or even an entire application) if the toggle hasn’t been disabled by a specific time-out period.

Visual cues to distinguish between a toggle’s on and off states are very important. Research indicates that using high-contrast colors and including state descriptors next to the toggle improves users’ comprehension. However, it is important to keep in mind that the inversion of a toggle — where the active state is represented by a darker color and the inactive by a lighter color — can be visually confusing for some users.