A toggle is a switch that has two positions, on or off. You can toggle something on or off by pressing it, for example a button on a laptop that turns the screen on or off. You can also toggle between two screens during a video chat. The word toggle comes from an 18th century pin that was passed through the eye of a rope to stop it from moving, but it has since been applied to many different kinds of switches and fasteners, like cordlocks (for stopping a cord or drawstring) and toggle switches on computer keyboards.

Toggle is a powerful tool for configuring specific service instances, but it’s easy to misuse. It’s important to only use this feature as part of automated tests or manual exploratory testing and debugging. It’s a best practice for teams to test the toggle configuration that they expect will be live in production and any fall-back configuration that will enable older or legacy features when the toggle is flipped Off. It’s also wise for teams to perform some tests with all toggles flipped On to help ensure that there aren’t any surprise regressions when new releases roll out.

When designing toggles, it’s essential to remember that users may rely on visual cues to understand their current state. For this reason, designers should consider implementing clear labels that describe the feature’s current state in addition to visual indications of active or inactive status. Using a darker color to denote the active state typically performs better than a lighter shade, but it’s crucial to remember that not all users will see the difference in shades — especially for those with red/green color blindness.