Toggle is a control that allows users to change the state of an element (either ON or OFF). Toggles are preferred when it comes to adjusting settings or preferences since they provide less ambiguity than radio buttons. Toggle switches should be clear and direct in their labeling and use visual cues like movement and color to convey the toggle’s current state. Ensure that toggles are clearly differentiated from other controls by using clear contrast and considering cultural implications when choosing colors for your visual signifiers.

In software applications, toggles can be used to perform multivariate testing or A/B tests. A toggle can consistently send a given user down one code path or the other, allowing for data-driven optimizations of things such as an ecommerce product configurator’s purchase flow, the Call To Action wording on a button, or the default theme of a web application.

Feature Toggles are a key component of newer agile development processes, which allow teams to release features and gather feedback on them before they’re fully developed. When a team is ready to bring a toggle into production they can merge it into trunk code and then hide it behind a feature flag until it’s needed.

It’s important to test all the toggle configurations that you plan to bring into production, including the fallback configuration (with everything flipped Off). To help prevent regressions, many teams also run a few tests with the toggles they expect to be live in production flipped On, so they can catch any bugs that may arise before a rollout.