Toggle is a feature of technology and computing that allows you to switch between two states or options. You can find toggles in everyday technologies like phones, tablets and computers as well as in software applications such as email programs.

Toggles are a key element in many Agile development practices. They allow developers to add new functionality to an application without adding any additional lines of code. This is useful for features that are still in progress or not yet ready for production. This type of feature can be managed through a variety of means from simple comments in source code to fully fledged feature flag management systems.

One of the most common uses for Toggles is to perform A/B testing on different code paths. A toggle will allow a given user to be sent down one codepath or the other, and then aggregate usage data can be used to determine which path is most effective.

A savvy team will treat their inventory of Toggles as something that comes with a carrying cost, and they should seek to minimize the number of idle toggles in the codebase. Some teams have a rule that they will always put a task in the backlog for toggle removal once it has run its course, and some will even implement “expiration dates” on their Toggle configuration so that a test will fail if a Toggle has not been re-configured within an acceptable amount of time.