Toggle is a software or hardware switch that enables you to choose between two settings or options. For example, the Caps Lock and Num Lock keys on a keyboard are toggle switches that enable you to turn specific functions on or off. You can also find toggle switches in many user interfaces, such as the options menus found in many applications.
In a release cycle, applying feature toggles is an effective way to delay the deployment of some new functionality until you’re ready to roll it out to your users. It’s important to remember that the features hidden behind a toggle need to be fully tested and QAed, and they should be ready for use in production before being turned on.
One challenge with using toggles is that it can be hard to understand which side of the switch represents the “active” state. This can be overcome by using high-contrast colors to differentiate the states and by adding in-state labels. In our research, the best toggles used clear visual cues to convey their status (with a more pronounced color for active and a lighter color for inactive) and included text to clarify which state they were in.
Another key benefit of toggles is that they reduce the need to continually verify how a release will perform with a particular toggle. As long as the toggle configuration lives side-by-side in source control, changing a toggle’s decision is as easy as rolling out a new release with the correct toggle set (for less dynamic flags at least). This helps to shorten the time between the toggling decision and when it goes into production.
