Yes! Firesheep was the extension, and I think the combination of that and LetsEncrypt (which was in part a reaction to Firesheep) were the reason the web went f

Yes! Firesheep was the extension, and I think the combination of that and LetsEncrypt (which was in part a reaction to Firesheep) were the reason the web went from almost entirely decrypted by default to almost entirely encrypted by default in a matter of months. The capabilities had been there for years, but Firesheep made session hijacking a literal one-click affair and vividly highlighted the danger of unencrypted web traffic - it’s maybe the most impactful bit of white-hat hackery of all time.