Grammar Matters: Whose and Who’s
I always get these confused, so much so that I avoid using either all together. Finally, I took the two minutes needed to refresh my memory and understand the difference between the two.
According to Paul Brians’ Common Errors in English Usage:
This is one of those cases where it is important to remember that possessive pronouns never take apostrophes, even though possessive nouns do (see it’s/its).
“Who’s” always and forever means only “who is,” as in “Who’s that guy with the droopy mustache?” or “who has,” as in “Who’s been eating my porridge?”
“Whose” is the possessive form of “who” and is used as follows: “Whose dirty socks are these on the breakfast table?”