What Is a Toggle?

A toggle is a kind of switch that can have two positions: on or off. It’s also a verb, as in “toggle between screens when video-chatting with two friends at once.” The word may also refer to a device that fastens something to a frame, or to a cord lock, which keeps a rope or cord from unwinding.

In web development, toggles are used to update preferences or settings. They’re simple to use and easy to understand, but they can be difficult to implement consistently across a site or app. Toggles should be labeled clearly and logically, with clear visual cues that make them stand out. They should be designed to deliver immediate results, and they should be consistent with other control elements such as sliders and arrows.

Toggle switches should be recognizable by their shape, size, movement and color. The color should be high contrast and have a strong association with on/off states. Designers should also take into account societal and cultural differences when choosing colors for toggle states, since some colors may be counterintuitive to users. For example, using red for on/off could confuse people who associate the color with traffic signals or stop signs.

When designing a toggle it is important to consider how it will be configured and managed in production. Managing toggle configuration via static files becomes cumbersome at a certain scale, and it can be challenging to ensure consistency across a fleet of servers. To address this challenge many organizations choose to move their toggle configuration into some type of centralized store, often an existing application DB. This approach is usually paired with some sort of admin UI that allows system operators, testers and product managers to view and manage feature flag configurations.

One of the most common uses of toggles is for multivariate or A/B testing. By defining distinct code paths for different cohorts of users, it’s possible to see the aggregate effect of each path and then optimize the overall behavior of the system. In the case of a web app this can mean changing everything from the Call To Action wording on a button to the order of the steps in an ecommerce flow. To do this it’s necessary to create a Toggle Router that will consistently send each user down one codepath or the other, and then measure the effects of this change. The results of this experiment can then be compared to the results of an identical, but non-optimized, version of the site to determine which changes have been most effective. The optimal version of the site is then rolled out to all users.