Added another major PHP security issue in their example code.
Added info on blocking w3schools through google account
Better answer regarding HTML 4’s case-insensitivity
Corrected typos and replaced "*pretty*" with proper emphasis.
add a note about filename extensions not being required at all for html
Probably too long and could be worded better. I can't figure out what license there is for this site/repo but feel free to edit mercilously. ;-) (as wikipedia's edit box warns)
Called out bullshit in descriptions of the cite, dl and header elements
…ts, plus a crap example of strong