What does it mean in HTML 5 when an attribute is a boolean?

Question

What does it mean when a property like a hidden property is a boolean property? Can someone explain it in layman's terms?

Answer 1

As mentioned before, a Boolean property is a property that evaluates to true or false.

However, according to the HTML5 specification - http://www.w3 .org/TR/html5/infrastruct.html#boolean-attributes

Please note that this means that is not allowed in HTML5 .

The correct thing to do is or or or any of them case insensitive and single quotes/no Quoted variant. All of these will evaluate to true.

Considered false only if the attribute is completely missing.