A toggle is a simple, powerful user interface component that lets people manage the state of content or a view. Use it when you need to let people choose between two opposing values that affect the current state of something—like a setting, view, or piece of content—and you want to deliver results immediately. Otherwise, opt for a different type of user-interface element like a button.
In software and hardware engineering, the word toggle describes a switch with two positions: on and off. For example, the Caps Lock and Num Lock keys on your keyboard are toggles that enable or disable specific functions. Likewise, toggles can also be found in options menus in nearly every application.
Although toggles are a convenient and user-friendly interface component, it’s important to ensure that they are designed and implemented consistently across an entire product. When a toggle is misapplied it can confuse users and negatively impact their experience. Toggle switches should be used sparingly, and only when it is important to differentiate between two opposing values that change the state of something (like a setting or a piece of content). Otherwise, opt for a more traditional user-interface element like a button.
Toggle switches should always have clear and obvious visual signifiers to help users discern their current state—like an icon or a label. They should never be hidden in an image or text and they should always be updated at runtime to reflect their current state. Additionally, designers should be mindful of color and consider societal and cultural implications when choosing a state indicator for a toggle switch. For example, a red on/off switch may not be intuitive for some users who associate this color with stop lights and traffic signals.
The word toggle can also be used in programming to describe an algorithm that allows for the dynamic re-configuration of specific service instances in response to user interactions with them. This is often referred to as an Experiment Toggle and is commonly used for A/B testing or multivariate optimizations on things like the purchase flow in an ecommerce system or the Call to Action wording of a button.
When creating a toggle configuration that will be deployed to production, it’s best practice for teams to test all possible combinations of the toggle being flipped On and Off. This is important to make sure that the release will perform as expected and will not introduce any unexpected regressions. This can be accomplished by using a tool like a CI/CD pipeline with preprocessor features or a more sophisticated approach such as a feature flag.
