.WEBBOOKMARK File Extension

Bookmark file created by Safari, a Mac OS X Web browser; saves a bookmarked Web page, including the Web page's title, URL, and bookmark group; used for saving and organizing favorites and other Web pages.

Bookmarks can be organized into multiple groups in Safari, including the Bookmarks menu group and the Bookmarks Bar group, which displays bookmarks horizontally underneath the application's Web address bar. Users can access all bookmarks by selecting Bookmarks → Show All Bookmarks in Safari.

Safari stores WEBBOOKMARK files to the following directory by default:
[user]/Library/Caches/Metadata/Safari/Bookmarks/.