A toggle is a switch that turns something on and off. It can be used in hardware (like the Caps Lock or Num Lock keys on a keyboard) or software (such as options menus found in most applications). Toggles are commonly seen to help users manage the settings and preferences for an application.
Toggle can also refer to a pin that is used to fasten a rope to its stay, mast, etc. A common use of this is to toggle the rope around the eye or bight of the stay to secure it.
One way that we might use Toggle is in the form of Feature Toggles which are used to make data-driven optimizations in production systems. A Feature Toggle is deployed to a particular cohort of users and at runtime the toggle router will consistently send them down one codepath or another, allowing us to see the effect of a change on the aggregate behavior of that cohort.
Savvy teams view the number of Feature Toggles in their codebase as inventory which comes with a carrying cost and try to keep it low by aggressively removing toggles once they have served their purpose. Toggle removal tasks are often added to the team’s backlog right after a Feature Toggle is first introduced and some teams even put “expiration dates” on their toggles to help them with this process.
When using Toggle in web pages it is important to ensure that they are designed so that they are clearly and consistently understood by all users. This means that they should always be accompanied by clear and direct labels which describe what the toggle does when it is on. It is also worth considering how the visual cues of the toggle will be communicated to visually impaired users. For example, it is a common practice to use colors to denote an active or inactive toggle but this has been shown to be unreliable for some users who have red/green color blindness.