An experimental flag is a hidden or non-default setting in software that allows users, typically developers or testers, to enable features that are still in development or testing phases. These features are not yet part of the main release and may be unstable or incomplete. Experimental flags are often used to gather feedback, test new functionalities, or debug issues before a wider rollout. Activating such a flag generally involves accessing advanced settings or using command-line options, and is intended for advanced users or those willing to accept potential risks. They are commonly found in browsers, apps, and operating systems.