Toggle is a simple user interface control that allows the user to update preferences, settings, or other types of data. When used correctly toggle switches are effective at conveying a clear message and delivering immediate results. However, if overused toggles can cause confusion and overwhelm users. To avoid this, be sure to use direct labels, consistent visual design, and deliver a clear message that the change will take effect immediately.
In general, the word toggle can be used to refer to both software and hardware switching. For example, the caps lock and num lock keys on keyboards are both toggles that turn on or off the function they control. It is also commonly used to describe any on-off option in a menu like the ones found in most applications.
When designing toggles, be sure to follow the standard convention of using an icon with a contrasting background, utilizing a clear label that describes the on or off state, and indicating the current state with a color or other visual cue. Also be sure to evaluate societal and cultural context when selecting a toggle color as certain colors have negative connotations.
Managing toggle configuration via static files becomes cumbersome once the number of toggles grows and can be a challenge to ensure consistency across a fleet of servers. To overcome this many teams move their toggle configuration into some form of centralized DB, often an existing application db. This can make it easy for engineers, testers and product managers to view and modify toggle configuration.