Who’s means who is or who has. Whose asks or tells who something belongs to. Read the sentence with the contraction expanded before deciding whether it needs an apostrophe.
Compare the contraction and the possessive
- “Who’s at the door?” means “Who is at the door?”
- “Who’s already signed in?” means “Who has already signed in?”
- “Whose notebook is this?” asks who owns it.
Whose also works outside a question
“The guest whose coat we found came back for it.” Here whose connects the coat to the guest. The apostrophe in who’s marks missing letters from is or has.
Try it
“___ finished the puzzle, and ___ pencil is this?”
Show the answer
Use Who’s for who has finished and whose to ask who owns the pencil.
See also Your vs. You’re.
