Toggle is a term commonly used in technology, computing, programming and communications to describe the ability to switch between two settings or options. Toggles can also refer to physical switches, such as those found on computers and other devices.

Toggles are a simple but powerful concept that can make it very easy to change the appearance and behavior of your website or application at a moment’s notice. They can be as simple or complex as you wish, but they all allow users to quickly change a previously set configuration without having to modify code or go back to the previous page.

Feature Toggles are a great way to implement multivariate or A/B testing on a website or application. Using a Toggle Router you can consistently send a given user down one code path or another based on their cohort, and then use data to drive performance optimizations such as adjusting the Call to Action wording on a button or changing the color of an UI element.

When designing a Toggle Switch it is important to be aware that toggles require a clear and direct label for their state, as well as a visual cue to indicate the current state. This is a common design problem and can lead to confusion for the end user when it is not addressed. Good toggle labels are short and direct, ideally only one or two words. They should also be placed next to the toggle switch with a short explanation of its function.

In addition to providing a clear and direct label for the current state of a toggle it is also important to consider cultural and societal implications when choosing the colors to represent on/off states. For example, the color red might have negative associations for some users, and it is important to evaluate a color’s meaning before deciding on a use case for it.

Finally, it is important to note that toggles may have a significant impact on a production system’s performance. This can be due to the number of toggles in a release or because of how the toggles are configured. For example, if a toggle is based on a database query it could be making thousands or even millions of database calls per release for a value that rarely changes.

Savvy teams view Feature Toggles as inventory that comes with a carrying cost and try to keep their inventory low by being proactive about removing unused toggles in a timely manner. This is typically done through a combination of commenting, hardcoding and a preprocessor’s #ifdef feature where available (but this approach doesn’t support dynamic re-configuration). Some teams may also place an expiration date on their toggles so that they are automatically removed from a release when it gets close to the time to remove them. This helps to ensure that they are not forgotten or pushed back into future releases.