A toggle is a switch that has two positions: on and off. You’ll see this kind of switch in the Options menus in most software applications. The word toggle is also used figuratively to refer to switching between functions, such as the way you might toggle between screens on your video chat with two friends simultaneously.

In web design, the term is most often used to describe a simple user-interface element that allows users to update preferences, settings or other types of information. Toggles help reduce clicks and allow the user to see immediate results based on the new state of the control. However, like many other UI elements, toggles have some issues that should be considered when using them.

Toggles should have direct labels that clearly indicate the purpose of the switch and its current state. If you use a color to distinguish the states of a toggle, make sure to use high-contrast colors that signal a change in state (e.g., red for ON and green for OFF). It’s also important to evaluate the societal and cultural implications of your choice of colors. For example, some people have red/green color blindness, so using green as the on position might not be helpful for them.

Another consideration is that a toggle switch can create confusion for users if it is used in the wrong context. For example, it’s usually not appropriate to use a toggle to hide elements that should be visible to the reader, such as an article’s map and vignette. These are essential components of the content that should not be hidden by a toggle.

Finally, it’s important to test toggle configurations that will eventually go live in production. To do this, most teams test both the current toggle configuration in production and a fall-back configuration with all of the toggles flipped On. This practice helps avoid surprise regressions in future releases.

If you have a feature flag system that supports runtime configuration, you can write a toggle in such a way that the value it sets in production will be reverted in a release. This is called blue-green deployment, and it’s an effective way to improve the quality of your code while still maintaining the ability to rapidly deploy changes.

There are several ways to hardcode a toggle, from a simple commenting approach through to more sophisticated approaches. The advantage of this approach is that the toggle configuration lives side-by-side with the code in source control and can be easily restored if needed. However, this type of toggle has some limitations, such as the need to deploy the entire release in order to revert a single toggle.

A more dynamic toggle configuration management is possible, but it will require a different way of thinking about CI/CD and deployment workflows. The trade-off is that you will need to implement a new kind of blue-green process to handle the additional work that dynamic re-configuration adds. To learn more about this approach read Managing Dynamic Toggle Configuration.