A toggle is a user-interface control that lets users update preferences, settings, and other types of information quickly and efficiently. Toggles should be clearly labeled, use standard visual design conventions, and deliver results immediately. They should be visually distinguished from other controls by the way they move or change color. It’s also wise to evaluate societal and cultural implications for color choices, as some colors may have different meanings to some groups of people.

When a toggle is flipped on, it means that the user wants to activate or enable a specific behavior. Toggles are most commonly used for binary actions such as “on/off” switches, but can be implemented for any type of on/off dynamic behavior.

The term toggle comes from a common figurative meaning in which something is “turned on and off.” A toggle is often found in machines, such as computers, where it allows the user to switch between functions. It’s also used to describe a mechanism that can be switched between two states, such as a door-opening system. In digital products, toggles are sometimes used to allow the developer to dynamically re-configure the product experience for certain groups of users based on data.

Using toggles for these purposes can be very powerful and effective, but it’s important to remember that they have to be configured at runtime. It’s easy for teams to over-reach with this capability, especially if they use toggles to dynamically re-configure features that are already live in production. This can cause confusion for existing users and potentially introduce bugs into the codebase.

It’s also very important to thoroughly test toggle configurations before releasing them into production. Many teams recommend testing the toggle configuration with existing or legacy behavior flipped Off, and then testing it again with new or future functionality flipped On. This can help to avoid any unexpected regressions that might occur in the future.

Another useful way to utilize toggles is for experimentation and A/B testing. By creating a toggle that routes some users down one codepath while others are routed down another, the experimenter can compare the aggregate user experience and determine which path is most effective. This type of A/B testing is commonly used to make data-driven optimizations to things like the call-to-action wording on a button, or the purchase flow in an ecommerce site.