How to Read the W3C Validator Part 1
This video tutorial series covers the many HTML5 error messages that the W3C Validator produces: what they mean and how to fix them along with strategies for identifying the errors at fault.
This is part one, and it covers the following errors:
"cannot recover after last error" 1:11
"element X is missing required child element Y" 4:18
"end tag N seen, but there were open elements" 5:11
"attribute X not allowed on element Y" 6:36 and it's related siblings: "element X is missing required attribute Y" 6:55 and "X element must have Y attribute" 7:17
"element X is not allowed as element Y" 8:35
everyone's favorite warning: "the N attribute is presentational markup. consider using CSS instead" 12:25
And who could forget the timeless classic: "unclosed element N" 13:38