The Toggle is a user interface control that allows a user to update preferences, settings or other types of information. Toggles are a great way to improve the cognitive experience of users by preventing them from having to make multiple decisions on each click. Toggles also help eliminate unnecessary clicking, which is especially useful on mobile devices.

In software development, toggles (or feature flags) enable teams to hide new functionality behind a temporary configuration until it is ready for release, product testing, or other milestones that would normally require code to branch out of trunk. This approach supports agile development methodologies and can allow companies to deliver new features more quickly to their customers.

The most important thing to remember when using toggles is to ensure they are labelled clearly. When users are presented with a list of options, each should be labeled explicitly with its on state and an off state to prevent confusion. Additionally, it’s generally best to use the simplest possible UI for toggles to avoid over-complicating the experience.

Toggle configurations tend to be temporary by nature so a smart team will make sure they are proactive about removing old toggles and reverting back to the default or fallback configuration when needed. Some teams even put “expiration dates” on their toggles so that the software will fail to run if a toggle is left in place past its intended expiration. These approaches vary in complexity from a simple commenting strategy through to more sophisticated techniques such as the preprocessor’s #ifdef feature.