A toggle is a switch that can be set to either of two states, or “on” or “off”. It’s used in everyday technology like smartphones and computers to control functions like WiFi or Bluetooth. Toggles are also found in software applications to control features or modes. They are commonly used in options menus where users can select the option they prefer.

The word toggle is an old English word, meaning a pin passed through an eye or loop in a rope or chain as a temporary fastener. It’s still used to fasten things, but now it usually refers to a button that’s pushed through a hole or loop to fasten the thing it’s connected to. It can also be used to indicate whether something is on or off, like the caps lock or num lock keys on a keyboard.

Feature toggles are a key tool for agile development processes and have become popular in the UX community as well. Rather than creating and testing new features on code branches, developers can create a toggle and deploy it to a small cohort of users for evaluation purposes. After the team has enough data to determine if the toggle is successful, they can take it live for all users and make the decision to move forward with the feature.

Toggles can be configured in a number of ways, from simple commenting on the code to more sophisticated preprocessors. Ideally, the toggle configuration lives side-by-side with the code in source control so that the state of the toggle can be restored to previous releases, or recreated from scratch if necessary. This is more practical for long-lived toggles, compared to those like Permissioning Toggles that must be configured on a request-by-request basis.

Designing effective toggles can be challenging. Users need to be able to easily identify which option they’ve selected and the current state of the toggle, so it’s important that designers pay attention to both contrast and cultural implications when selecting visual signifiers for these switches. For example, choosing the color red for the on position could be problematic for some users who associate it with stop signs or traffic signals.

Savvy teams look at the inventory of toggles in their codebase as assets which come with a carrying cost, and work to keep the inventory low by being proactive about removing unused ones. This can be as simple as adding a task to the team’s backlog whenever a new toggle is introduced, or more complicated such as setting an expiration date for an existing toggle. This makes it easier for teams to plan for the eventual removal of a toggle without disrupting their production environments or breaking any other features. Ultimately, this allows them to deliver the best possible experience to their users. For more information about designing effective toggles, check out our article on this topic.