A toggle is a switch that can be set to either the “on” or the “off” position. It’s commonly used in technology, computing, and programming to enable or disable features. You can find toggles in everyday devices such as smartphones and computers. A toggle is also a common feature in software applications that allow users to select between different settings or modes.

Creating and using toggles allows teams to test and implement new features in an isolated way while the rest of the system continues to run normally. This makes it a great tool for doing A/B tests or multivariate experiments without risking the integrity of the production environment. Toggle switches can be used to experiment with things such as the purchase flow in an ecommerce system or even call-to-action wording on a button.

Toggle switches are a useful design tool to have in your arsenal, but it’s important to use them sparingly and only when they are necessary. Too many toggles can confuse and degrade the user experience of an application. If you are going to use toggles, it is best to maintain a consistent style and make them easy to identify with clear labels and visual cues like color changes.

Using toggles can also increase the complexity of an application’s code base and introduce bugs that are difficult to reproduce or track down. For this reason, it is important to keep the number of toggles low and create a process for vetting whether they are the right solution to a problem. It is also recommended to use an admin UI that separates toggle configuration from the application’s main config file to avoid this increased complexity and make it easier for teams to manage and debug their toggles.

Another common use of toggles is to implement a Canary or Champagne Brunch Release. This is a method for doing A/B testing on specific cohorts of users. In this case, the Toggle Router is configured to consistently send a given cohort down one codepath or the other. Then the results of the experiment can be analyzed to determine if the change is worthwhile or not.

Toggle configuration can be stored in static files or in a database, but as your usage grows it’s worth considering moving to a centralized system. Modifying these files becomes cumbersome at a certain scale, and managing the configuration of multiple servers across deployments is difficult. This is why a centralized toggle system often includes some type of admin UI that allows teams to view, modify, and delete their toggles as needed.