But, userscript managers do a lot more than execute scripts, and screen for the pages they are intended to run on.
The most common operations performed by a userscript manager include installing, organizing, creating, copying, saving, deleting, and editing (including modifying webpage permissions of) userscripts.
Metadata can also include information that is useful to the user such as the script's name, author, description and version number.
Popular userscript managers include Tampermonkey, Greasemonkey, and Violentmonkey.
The metadata contains specific delimiters which help the userscript manager distinguish it from ordinary JavaScript files, along with configuration parameters used during installation.