A toggle (or a toggle switch) is a user interface control that allows users to choose between two states or options. Toggles are widely used in technology, computing, and programming to allow users to update their preferences or settings. They are more intuitive than checkboxes or radio buttons and often require less screen space.

The most important consideration when using toggles is making sure that the control’s current state is easy to understand. Toggles should have clear, direct labels that describe what the switch will do when it is on or off. It is also best to avoid relying on color to convey meaning as this can be confusing for some users. In particular, people with red/green color blindness might not be able to distinguish between green and red toggles which can cause confusion and mislead users.

In most cases, a toggle should be used to change a setting or option and should not be able to be changed back to its previous state. For example, a toggle should never be used as a download button because it can mislead users into thinking they will continue downloading even when the toggle is off. In addition, it’s best to avoid presenting a toggle as a choice that will have long-term consequences.

When a toggle is used to implement a feature flag it is recommended that teams test both the current production toggle configuration as well as the fallback configuration where those features are flipped Off. This helps teams to verify that any new releases will not cause a regression in the existing behavior of the product.