No, that’s not valid HTML, but to the annoyance of pedants and purists everywhere, this is spec-compliant HTML that doesn’t even generate a warning in the validator:

〈!doctype html>
〈html lang="en">
〈title>Hello〈/title>
〈p>world

Always remember to save dozens of bytes by ignoring optional closing tags and unnecessary opening tags! You’ll save microseconds of network transfer time and piss off dozens of people who inspect your HTML!

Edit: damn you, Lemmy, stop stripping my tags! Just pretend 〈 is the real less-than character because Lemmy strips it out.