Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
The external property of the Window API returns an instance of the External interface, which was intended to contain functions related to adding external search providers to the browser. However, this is now deprecated, and the contained methods are now dummy functions that do nothing as per spec.