Toggle is a word used in both software and hardware to describe a switch that can be either ON or OFF. It’s a common feature found in every options or preferences menu in many applications and is also the preferred control for changing settings on mobile devices. It is generally considered a better option than radio buttons because it takes up less screen space and has a more clearly defined result (i.e ON or OFF).

Savvy teams consider their Feature Toggle inventory to be a kind of inventory with a carrying cost, and so are proactive about removing toggles that have served their purpose. Some teams even put “expiration dates” on their toggles, so that they will fail a test or even refuse to start the application if they are still configured after a certain date.

The ability to toggle the configuration of a service instance at runtime is an extremely powerful tool, and it should be reserved for the most critical or performance-critical settings. It can be tempting to use it for less-critical or customer-facing settings, such as the default call-to-action text on a button, but this will quickly degrade the user experience by adding unnecessary delay to the time it takes for changes to take effect. To avoid this issue, it is recommended that a toggle be replaced with a simple checkbox in these cases. This will keep the user experience consistent and provide immediate results.