These two words are frequently confused because they sound alike. However, they don’t mean the same thing, and there is an easy way to remember the difference.
Who’s is a contraction for who is. Just remember the apostrophe lets us know there are letters missing. In this case, the apostrophe replaces the “i” in is. Example: Who’s (who is) going to clean up this mess? Who’s (who is) coming over today?
Whose is a possessive pronoun. Just as the description implies, it is possessive, meaning it signifies ownership. Examples: Whose book is that? Whose keys are these?
That little apostrophe causes confusion with several pairs of words that sound alike – it’s vs. its and you’re vs. your. Be sure to check out my Grammar Tips for ideas on overcoming those stumbling blocks