Toggle is a user-interface element that lets users update preferences, settings, or other types of information. When used well, toggles can make it easy for people to manage a feature’s state—whether it’s On or Off. However, it’s important to avoid using toggles in places where they might confuse or distract people. When you do decide to use a toggle, be sure to provide direct labels, use standard visual design, and deliver immediate results.

Historically, toggles were pins or bolts passed transversely through a chain, eye in a rope, or loop in a fabric. Now, they’re often found on computers and other machines where a toggle switch is used to turn functions on or off. A toggle can also be the rod-shaped button that inserts into a large buttonhole, loop, or frog on a jacket or shirt. It can also refer to a metal device for fastening a toggle rail to a frame.

The word toggle may also be applied to a series of actions or a period of time: He was toggling back and forth between lucidity and sleeplessness. The brain continues to toggle between non-REM and REM sleep throughout the night, alternating between the two states.

A toggle can be a useful tool when you want to give someone control over a process that may have unforeseen consequences. For example, if you’re using a toggle to enable or disable the send function on an email program, you would want to ensure that the user is aware of how their choice will impact the overall workflow.

There are several different approaches to managing toggle configuration in code, ranging from approaches that are simple but less dynamic through to some options that are quite sophisticated and require a lot of additional complexity. However, regardless of which approach you choose, it’s a good idea to test all toggles that you intend to release with both flipped On and Off. This will help you avoid any surprise regressions that might occur if the team forgets to change the toggle configuration before releasing the feature.

A toggle’s state can be conveyed by its color, but you should avoid relying solely on this cue to signal state. For example, some users have red/green color vision deficiency, so a toggle that uses green as the on position might not be meaningful to them. Also, consider the societal and cultural implications of your choice of colors. For example, some cultures associate the color red with stop signs and traffic lights—not a great symbol for an active toggle. If possible, use a high-contrast color to signal state and add clear, concise text or icons to indicate the current state. This will allow users to understand what they’re doing and will help them avoid errors. Adding a label that indicates which side the toggle is on (or off) also helps. This is especially helpful for users who are new to a web or app interface, as it will clarify what they’re doing and what the effects will be.