A toggle switch is a piece of user-interface that allows users to update preferences, settings or modes by enabling or disabling features. They are commonly used in everyday technology such as phones, computers and tablets, and in software applications to control the behavior of features.

In the case of a bug fix, creating a toggle can help ensure that the fix doesn’t accidentally worsen the problem. However, a toggle also introduces extra complexity into the code, so it is generally better to decide on a case-by-case basis whether or not a toggle is needed.

A common way to use toggles is for A/B testing. By defaulting a feature to ON and then turning it off for a subset of users, the engineering team can test a new version of an application without risking their production users.

It’s important that all toggles are easy for users to understand. A toggle that looks like the one shown below has clear labels that make it easy for users to see what state the toggle is currently in. The labels should be short and direct, with a maximum of two words. Using colors is often an effective way to communicate a toggle’s status, but it’s important that designers take care not to rely on color alone. For example, if a toggle uses green for ON and red for OFF, this could be confusing for some users with red/green color vision deficiency.

Savvy teams view the toggle configuration that they plan to release as inventory with a carrying cost, and are proactive about removing any toggles that are no longer required. They will also usually test their releases with both the current toggle configuration and the toggles they intend to release flipped On, to avoid any surprises caused by unexpected regressions due to the removal of a toggle that was previously enabled.