A toggle is a switch with two positions, on or off. It’s also a verb that means to alternate, like when you toggle between screens as you video chat with two friends at once.

Toggles are often used in user interfaces to allow users to update their preferences or settings. They provide a more concise alternative to radio buttons or checkboxes and can be more intuitive for users since they only need to select one option instead of multiple. However, using toggles requires extra care to ensure they are properly labelled and designed in order to be effective.

In addition to being easy to understand, it is important for toggles to deliver immediate results. This can be a challenge for systems that take a bit of time to change their state (e.g. a video streaming service) but there are ways to mitigate these problems. In this case, adding a processing status loop animation can help users see that their selection is taking effect and can reduce the frustration associated with delayed system responses.

Another way to improve the user experience of toggles is by providing visual cues that differentiate between their active and inactive states. For example, a more pronounced/saturated color for the active toggle can be helpful in attracting attention and increasing initial performance. This increased performance can quickly diminish, however, once users have spent more than a few seconds thinking about their choice. A more subtle design approach that uses a different color for the inactive toggle can improve perceived performance even further, though it is important to avoid inversion of these cues as this can confuse users.

Savvy teams recognize that each toggle in their codebase comes with a carrying cost and seek to keep this inventory low. This is usually accomplished by ensuring that any released toggle is only kept in production for as long as necessary and removed once it has been determined to be stable. This practice is known as blue-green deployment and helps to avoid a potential disaster caused by a single unstable toggle that could affect all users of an application.

As the use of feature toggles becomes increasingly commonplace it’s worth highlighting some best practices when implementing them. Firstly, it’s important to understand that toggles should only be used where there is a clear need for them – i.e. to allow users to change a pre-selected default state such as ‘Airplane Mode ON’ or ‘OFF’. If you are attempting to create some other type of dynamic behaviour a different UI component such as a dropdown or radio button is likely to be more appropriate.

Using static files to manage toggle configuration is cumbersome at scale and can introduce errors due to the hardcoding of if-else statements. In order to avoid this issue many organizations move their toggle configuration into some type of centralized store, often an existing application DB. This is usually accompanied by the build-out of some form of admin UI that allows product managers, engineers and testers to view and modify these toggles.