A toggle is a hardware or software switch that allows users to turn on or off functionality. A toggle is often used in hardware, such as the Caps Lock or Num Lock keys on keyboards or in software, such as options menus for desktop applications.

In software development, a feature toggle is the simplest way to enable and disable a new feature. A wide variety of conditions can be used to determine whether a toggle flips or stays put, including fitness test results from other features in the codebase, settings on your feature management platform, or even variables provided by config files.

While toggles can be an important tool for teams, it is also important to be thoughtful about when and where they are used. Toggles should only be deployed when they represent mutually exclusive states of a function, and they should be named with clear, direct labels. This will make it easy for someone else on your team to understand the purpose of a particular toggle, and reduce the risk of mistakes.

A major benefit of using toggles is that they support more agile development processes by allowing dev teams to create and release software with new features that are still under development. Traditionally, those features would have been written on a separate code branch and then merged back into trunk code, which would require a significant amount of time for QA and marketing to test and review before they were ready to be released to the public.