Toggle is an HTML UI element that lets you change your site’s behavior by turning on or off options and settings. It can be used for displaying or hiding content, changing form fields, and more.

Toggles work best when they help users update preferences, settings, and other types of information that aren’t necessarily permanent or time-sensitive. They’re a great way to allow people to make quick changes without the need for code refactoring or other costly updates, but it’s important to think about usability and accessibility before implementing one. When done poorly, toggles can confuse users, create cognitive stress, or cause them to abandon a page. To avoid these problems, design your toggles with clear, direct labels and standard visual design.

When a toggle is in the right position, users understand that it means something is either on or off. However, if the toggle isn’t in the right position or it doesn’t look like a typical toggle button, users may be confused and will likely lose confidence in your interface.

For example, consider the top toggle in this article. This is a good example of a well-designed toggle because it follows the proximity principle and looks like most other toggles online. But the bottom toggle looks more like a radio button, and isn’t in the same location. This could cause confusion for some users who might not expect the same behavior from the toggle and be surprised to find they’re getting cookies all of a sudden when they click on it.

Using feature flags supports newer agile development approaches that allow teams to release software even while features are still in progress. Normally, such features would need to be written on code branches and go through a lengthy testing and review process before being merged back into trunk code. But with the right tools, developers can hide these features behind toggles until they are ready for release or a specific user audience.

One common approach to implementing toggles is to hardcode the current state of a release in the source code through comments or preprocessor features (like #ifdef). This has the advantage of allowing teams to test releases with all toggles flipped Off, but it’s important to note that the toggle configuration can only be changed by redeploying the release.

Savvy teams view the toggles in their codebase as inventory that comes with a carrying cost, so they seek to keep the number of feature flags as low as possible. To do this, they regularly audit and remove toggles that are no longer needed. Some teams even set “expiration dates” for their toggles so they fail a test or refuse to start an application if the feature flag isn’t removed by a certain date. Using structured configuration files, establishing clear ownership of toggles, and regularly cleaning up toggles all contribute to a healthy codebase that balances flexibility with maintainability. If implemented correctly, toggles can be a powerful tool that improves code quality and allows teams to deliver better experiences to their users.