It's always means it is or it has: “It's raining.” Its (no apostrophe) shows belonging: “The dog wagged its tail.”
Who's means who is or who has: “Who's coming?” Whose asks about belonging: “Whose bag is this?”
The trick is to try the long form. If “it is” or “who is” makes sense, use the apostrophe. If not, leave it out. Remember that possessive pronouns like his, hers, its and theirs never take apostrophes.
Worked example
Choose: “The bird built ___ nest in the tree.” (its / it's)
- Try it is: “The bird built it is nest” makes no sense.
- So it shows belonging: its.
Answer:The bird built its nest in the tree.
Key words
- contraction
- a short form with an apostrophe
- possessive pronoun
- a word like its, hers or theirs that shows belonging
- confusable
- words that are easy to mix up
Practise this
New questions every time.
Common Core-referenced: L.4.1g