A toggle is a switch that can be placed in either of two positions, on or off. Toggles help users update preferences, settings, and other types of information. When used appropriately, toggles can make a big difference to user experience. However, they must be implemented carefully and thoughtfully to avoid creating confusion or frustration. Toggles should always be clearly labeled, based on their current state, and use standard visual design elements to communicate their states. Using high-contrast colors for toggles can help users differentiate them from other components of a system, and clear state descriptors can be helpful as well. Toggle switches should also be consistent with their physical counterparts, as users are accustomed to seeing them move between positions in real-world systems.
Toggle configuration is best managed in some type of centralized store. In most cases this will involve a combination of existing application DBs and some form of admin UI which allows product managers, testers, and engineers to view and modify feature flags. Some teams even go as far as putting “expiration dates” on their toggles which will fail a test (and even refuse to start an application) if they have not been updated in some time.
When a team is considering adding a new toggle to the product it is important to evaluate the amount of work that will be required to maintain it once it has been deployed to production. It is also critical to determine whether the benefits of having the toggle available outweigh the overhead associated with maintaining it. If the answer is yes then a Champagne Brunch or similar release plan should be considered which will allow the new toggle to be exposed to a small cohort of users for a short period of time while the product manager and engineering teams can perform manual and automated testing against it.
A toggle can also be used to perform multivariate or A/B testing within an application. A specific cohort of users is sent down one codepath and the results are compared to the aggregated result for a different cohort which was sent down the other path. This is a very effective way to quickly make data-driven optimizations to things like the purchase flow in an ecommerce system, or the Call To Action wording on a button. Because of the nature of a toggle it is usually not appropriate for an experiment to run over a sustained period of time. However, a toggling decision that is baked into the release process and then changed by rolling out a new version with a toggle configuration change is very common. This is often referred to as a Toggle Upgrade.
