[ralphm]

Google Search used to have such a feature. I used it to blacklist w3schools. Of course, the feature is no longer there.

[chocolateboy]

If you're using Firefox: https://addons.mozilla.org/firefox/addon/hide-w3schools/

[SmellyGeekBoy]

What's wrong with w3schools? I occasionally find their site useful for basic HTML stuff and it seems inoffensive enough, certainly compared to others mentioned here (Quora, LinkedIn, Pinterest et al)

[hk__2]

w3schools used to be a very bad resource but it has improved over the years. See https://www.w3fools.com/.