A toggle is a switch that can be activated or deactivated to allow the user to change between two states or options. Toggles are commonly used in technology, computing and programming to provide the user with a way to control their settings and modes. When a toggle is active, it switches to the desired state and when it is deactivated it switches back to its default state.

The toggle is a useful element to have in your toolbox, but you should be careful with how and when you use it. It’s important to understand the cognitive issues around using a toggle and consider alternatives such as checkboxes or radio buttons.

The word toggle has many different meanings, from a small pin passed through the eye of a rope to bind it temporarily, to the up and down operation of a light switch. It’s also used in software as a way to control functionality which is switched on and off on an intermittent basis, like the Caps Lock and Num Lock keys on a keyboard. It’s also often used in UI design to describe the ability to change the state of a widget or element, for example by clicking it once to turn it on and again to make it off.

In code, a toggle is implemented as a Boolean variable. A toggle is on when the value of the variable is True and off when it’s not. Toggle switches are often visually designed to be recognizable by the user as such, for example by utilizing color and movement in their appearance. They can be confusing for users because there is no clear indication of the default or “off” state, so it’s essential to clearly label them and avoid confusing users by having more than one switch on a page.

There are several ways to implement a toggle, the most straightforward of which is through hardcoding it in the source code, either directly within an element or via a preprocessor such as #ifdef. This approach is incredibly flexible but lacks the dynamic re-configuration of a toggle that other options offer.

Another option is to use an external feature flag service which will manage the re-configuration of a toggle. This has the advantage of allowing developers to test toggles with real users on a live site and provides more granular control over the impact scope of the toggle.

Both approaches have their advantages and disadvantages, and you should choose the one which best suits your needs. However, it’s important to remember that a toggle should only be used in a limited context, as it can be quite disruptive and difficult for users to navigate. Other options should be considered instead, especially for those users with accessibility requirements or who require a more predictable and familiar experience. For these reasons it’s best to avoid using toggles in a public-facing environment, and to use them only within the scope of an internal experiment.