[marcan_42]

It used to be an extension (an official one from Google, Personal Blocklist). It was never part of the vanilla search results page itself.

[ComputerGuru]

No, it used to be part of the official results before the personal blocklist extension ever existed. Then some features were removed from the search results and then partially reimplemented in that extension.

[goodmachine]

Personal Blocklist by Google has been forked and reimplemented by a number of people:

https://chrome.google.com/webstore/detail/personal-blocklist...