Toggle is a term used in technology to describe a switch that can be either on or off. You can find toggles in everyday technology like smartphones, and software applications to enable or disable features. Toggle is also found in programming to refer to a simple way of enabling or disabling different code paths.

Feature toggles are useful for performing multivariate testing on a production environment without exposing users to risk. A feature toggle buckets users into two groups, when the toggle is flipped on they see a new version of your application with the tested behavior, and when the toggle is flipped off they see the original version of your application. This allows engineering teams to rapidly test and monitor the performance of new code without affecting any real users.

Operational toggles are also commonly used to temporarily disable non-essential features during high latency periods. This serves as a circuit breaker for your application and helps you manage latency issues while maintaining user experience.

Toggle labels should be clear and specific so that the current state of a feature can be easily understood by the user. The best way to do this is to use visual cues such as movement and color to help convey the current state of a toggle. Toggle switches should look more like sliders than checkboxes, and avoid using colors that rely on proximity (like red) to convey meaning.

When managing your toggle configuration it is often necessary to move away from modifying them directly in static files to some sort of centralized configuration system. Typically this is done by building out a front-end admin UI to manage and remove toggles. This can also be helpful in reducing technical debt as you start to remove old toggles that are no longer needed.