These are some tricky ones, and even people who kinda-sorta know them will still call me up to ask which spelling to use in a particular sentence. (Which, in fact, someone did just the other day.)
The way most people remember these is that “it’s” with the apostrophe is a contraction: “it is.” It’s the same with “who’s”: “who is.” But I remember them from the opposite direction, and if the spellings of these two pairs give you trouble, you might try thinking of them as I do. To wit:
“It” and “who” are pronouns. Just like “I,” “he,” “they,” “we,” and “she.” And the possessive form of a pronoun does NOT have an apostrophe:
- I → my
- He → his
- They → their
- We → our
- She → her
- It → its
- Who → whose
If you can remember that “it’s” and “who’s” are contractions AND that “its” and “whose” are possessive pronouns, you’ll double your chances of getting those spellings right.
You’re welcome 🙂
Katherine Wikoff 