A toggle is a switch that can be used to change state or mode. It is often used in technology, computing, programming and communications to allow users to adjust settings or modes quickly and easily. Toggle switches are also used in user interfaces (UI) as an alternative to radio buttons.

Toggles are best suited for changes in the system settings and preferences rather than actions that require the user to answer a yes or no question. For example, a toggle is the right control when you want to give users the ability to turn Airplane Mode ON or OFF. This kind of change is typically a one-time action that will not reoccur or have an impact on the system unless the toggle is reactivated.

Unlike other controls, a toggle has two states: ON and OFF. Because of this it is important to design the UI around the toggle carefully to help users understand what state they are currently in and how they can change that state. This requires that the designer understand the problem statement and target users.

Many teams choose to store the toggle configuration in some type of centralized source control — either through an existing application DB or through an UI-based admin tool. This is because modifying toggle configuration through static files can become cumbersome at scale and it’s difficult to manage changes consistently. Additionally, many teams find it is easier to test a release with all toggles flipped On if the toggle configuration is stored side by side with the source code.

Another use of Toggles is to perform multivariate testing or A/B tests in a production environment. This is accomplished by adding an experiment toggle to a feature and assigning users to one of two different cohorts when they load the feature. After a period of time the team can analyze the data and determine which variant of the feature is more effective. Then the team can roll out the favored variant to all users.

Using toggles as an instrument of experimentation is a great way to learn and improve the design of your product. However, it is important to keep your inventory of toggles low and have a process for vetting when they are no longer necessary or have run their course. Otherwise, you may end up with a lot of unused toggles in your codebase which increases maintenance overhead and creates cognitive overload for your users. Fortunately, many tools are available to help you prune your toggles and manage the lifecycle of your feature flags. This includes automated and manual processes to identify and resolve broken or unneeded toggles. Toggle pruning should be included in your continuous integration and delivery workflows. Ideally, these tools should integrate directly with your CI/CD pipeline to reduce the need for human intervention. For larger releases it’s also wise to have a set of test cases which are run with all of the feature toggles flipped On to ensure that your changes do not introduce regressions in production.