It's the same logic as with DRM: it won't prevent anybody from doing what they want, but it will stop a significant part of them. Right now websites have no wa

It's the same logic as with DRM: it won't prevent anybody from doing what they want, but it will stop a significant part of them. Right now websites have no way not to deliver inappropriate contents. The best they can do is to ask "are you 18+?" (see for instance Reddit), which a 3 years old could bypass. A basic protection against accidental view and/or kids a bit too curious could be as simple as: A) Have the adult sites to insert a HTTP header marking them as such. They have no reason from doing it, plus not delivering porn to kids is a legal requirement in most countries (or I guess so). This is a flexible solution for sites with mixed contents such as Reddit, because the mark is per-page. B) Have browsers not to show these sites if the 'adult content' is not ticked in the user profile. C) Make a tutorial that explains how to create restricted user profiles on their computers (so they can prevent their kids from using browsers that don't support this policy). Alternatively, but it would impact too much websites I guess, is to use a "safe for kids" header and have browsers to only show such sites etc.