Article: "Who's" is the contracted form of "who is" and is suitable for use only where the non-contracted form would also be suitable. Ex. "Who's coming to dinner?" "Whose" means "of whom or of which" and is a possessive pronoun, meaning it must be used to modify another noun. Ex. "Whose car is blocking mine in the driveway?" In question form, "whose" can modify a noun that isn't explicitly mentioned. Ex. "Have you ever heard her music?" "Whose?" "Kelly's."

What is a summary?
Use "who's" as instructed. Use "whose" as instructed.