Firefox Search Filters

Character Filter By
^ browsing history
* bookmarks
+ tagged bookmarks
% currently open tabs
# every search term is part of the title or part of a tag.
$ every search term is part of the web address (URL). The text “https://” or “http://” in the URL is ignored but not “file:///”.
? search suggestions

https://support.mozilla.org/en-US/kb/address-bar-autocomplete-firefox#w_changing-results-on-the-fly