When do you use whose?

The Word "whose" is a possessive or interrogative pronoun. Instead of saying "Who owns this pencil?" you can say "Whose pencil is this?"

Example sentences:

• "Whose trash is this on the table?"
• "I talked to the boy whose bike had been stolen."

Note:

The apostrophe form "who's" is not the possessive, but rather a contraction for the phrase "who is."

(See the Related link.)