A toggle switch is a control that shows a pair of opposing states, such as on and off, with different appearances. It’s a preferred way to adjust settings on mobile devices over radio buttons because it takes up less space.

It’s also a good choice when you need to enable new features for some groups of users, but not others. For example, a website might use a toggle to test out a new chatbot, but keep it off for the rest of the user base.

Toggle switches are the preferred design element for changing system settings or preferences because they’re easy to understand. They’re also often used for enabling features that require some level of trust or permission from the user.

While it’s tempting to put large swaths of code under the control of a complex series of toggles, it’s best to keep the scope of each toggle as small as possible. Larger toggles are more confusing for your teammates and a nightmare to debug weeks or months down the road when they start impacting other teams’ work.

Many teams use feature toggles to support agile development approaches that allow them to release software even while they’re completing code sprints on new features. Under more traditional waterfall development models those newly requested features would typically be written on separate code branches, requiring them to undergo a lengthy testing and QA process before they could be integrated back into trunk code. Using feature toggles allows those changes to be made right on trunk without the additional delay.

One of the most important things a team can do to improve the usability of their toggles is to name them clearly and consistently. It’s not uncommon for a toggle to be misunderstood if it isn’t given an intuitive name that helps people understand what it does. If you have a number of toggles that perform similar functions it’s helpful to group them together under an umbrella name which makes sense for the overall context of the toggles.

Managing the configuration of a toggle varies by platform and approach. There are many options available ranging from fairly simple but static approaches through to highly dynamic and sophisticated ones. Most teams will find that a combination of approaches is necessary to cover the full range of use cases for feature toggles.