The word toggle means “switch or alternate.” It’s a great choice when a control needs to allow users to select between two opposing states, like on and off. For example, a toggle switch would be the preferred way to allow users to update their device settings (like airplane mode). It’s also better than a checkbox when it comes to updating preferences or other types of information. In all cases, it’s important that toggles are used consistently to avoid user confusion. Toggle switches should also be provided with direct labels and be designed to look similar to sliders. Finally, it’s a good idea to make sure that toggles deliver immediate results so that users don’t need to click a Save or Confirm button to apply the new state.
The most common use of toggles is in conjunction with feature flags. When a feature is rolled out as either Canary or Champagne Brunch the toggle can be set to either On or Off for a particular cohort of users. This allows teams to perform multivariate or A/B testing and to drive improvements based on the results of that experiment.
Typically, a toggle configuration will live side-by-side with the release version in source control and can be changed dynamically during a deployment. However, some teams opt for a more hardcoded approach to managing toggle configuration such as using a preprocessor’s #ifdef feature or adding an expiration date to the flag. In any case savvy teams view the number of toggles in their codebase as inventory which has a carrying cost so they seek to keep that count low.