A toggle is a piece of material that can be pushed through a loop or hole to fasten it. It is commonly used in technology, computing, programming and communications to allow users to switch between different settings or states. The word is derived from the Latin toga, meaning “switch”.

In UX terms a toggle is a button or control that enables users to update preferences, settings, and other types of information. Toggles are user-interface elements that are easy to understand and deliver immediate results. Toggles should be designed with clear, direct labels and a standard visual design. In the web, toggles can be used to display dark or light themes on a website. They can also be used to show or hide certain content, such as article links and spoiler buttons.

As with any user-interface element it is important that designers use toggles sparingly and thoughtfully. In general, a toggle should only be used when there is a distinct user benefit to doing so. In most cases this will be when the toggle can significantly change the appearance or behavior of a page or application.

Toggles should always be clearly labeled and have a distinctive visual style. In addition to their primary role of displaying or hiding content the visual design should help communicate the meaning and purpose of the toggle. In addition to the obvious On and Off states of a toggle it can be useful to provide an additional or alternative state that indicates when a toggle has been activated. In this way a toggle can be designed to meet the needs of diverse users.

When designing a toggle it is critical that it is well tested. This is most important for the toggle configuration that you intend to release into production where it’s essential to test that all of the toggles that will be flipped On are correctly configured. It’s also wise to test the fallback configuration which will be active if a toggle is not flipped On. In order to avoid regressions it’s a good practice to include toggles in your tests that will cause the system to fail or behave in an undesirable way if they are not properly triggered.

When you start to scale the management of feature toggles via static files begins to become a significant problem. This often leads to the need to build out some form of centralized toggle configuration storage typically based on an existing application DB. In some cases this is accompanied by the need to build out an admin UI to allow product managers, testers and system operators to view and modify toggle configuration.