A toggle is a switch that can be set to either on or off. A common use of this type of control is to enable users to select an option or preference, such as when a user can toggle Airplane Mode ON or OFF on mobile devices. Toggles are particularly suited for this type of control because they take less screen real estate than radio buttons. When designing for toggles, it is important to be mindful of the context and provide clear labels that describe both the option being selected and the current state of the control (i.e. ON or OFF). It is also important to consider societal and cultural differences when selecting colors for state descriptors as well as ensuring that the design is consistent with other controls in your product.

Toggles are also used as a way to perform experimentation and A/B testing by allowing developers to test different versions of a feature on a subset of users. This is typically done using a Toggle Router that will consistently send a given user down one or another code path. This allows for the comparison of the impact of the different versions of a feature on metrics such as conversions or retention rates. This type of feature management is commonly referred to as a Champagne Brunch release or Champagne Brunch deployment and requires the use of a feature flag service or feature management platform.

When it comes to releasing features, the ability to turn toggles on and off at will gives teams the freedom to push updates faster. However, the risk of a toggle being left on too long can have negative effects on users. For this reason, it is important to make sure that toggle configuration lives side by side in source code so that changes can be rolled back quickly.