Not that I have to tell anyone, but this is tremendously useful for filtering out the flood of over-optimized garbage sites polluting the search indices nowadays.

For installation instructions see the link. (Tl;dr: Install the browser extension TamperMonkey, then click the green “Install this script” button on the page.)

(While there are also browser extensions for filtering search results, even ones that are purportedly open-source, the problem is that one has to trust that the program one installs is the same as the code in the github repository. With user scripts, on the other hand, one can see exactly which code gets installed and run, so that one only has to trust the Tampermonkey extension, and this extension is recommended by the Chrome web store and monitored for security by the Firefox web store.)