A toggle is a switch between two settings — for example on and off. It’s common for users to be confused by this, especially if they encounter it for the first time, and designers often add colors or other cues to make them clearer (which is good, but it doesn’t help people with red/green color blindness).
The word “toggle” originated in 1828 as a pin passed transversely through an eye or loop in a rope or chain to bind it temporarily, such as when setting sail. It became a noun in the 1860s. A toggle is also a small rod-shaped button for inserting into a large buttonhole, loop, or frog, and used especially on sports clothes. A toggle is also an ornamental rod-shaped fastener for a gate, door handle, or similar device.
Toggles are commonly used as a mechanism for doing multivariate or A/B testing. The toggle router consistently sends a given user down one codepath or another based upon which cohort they belong to and allows teams to track the impact of different changes on the behavior of their users.
Like any inventory toggles come with a carrying cost — they need to be maintained and kept in good working order. Savvy teams consider the number of toggles in production as an important metric and are proactive about removing toggles that they no longer need. Some even put “expiration dates” on their toggles to prevent features from accidentally being exposed to real users after they have been deemed unsuccessful in some way.
