Possession Without Apostrophes

Neither of these sentences makes sense:

"Who's hat is it?" Means "Who is hat is it?"
"It's power output is 60 watts." Means "It is power output is 60 watts."

Instead of using apostrophes, the English language has possessive versions of who and it:

Whose hat is it?
Its maximum power output is 60 watts.

Think of the words his and hers. Both end in s, but have no apostrophe. These are examples of possessive pronouns.