its/it's · whose/who's · their/there/they're
Distinguish possessive 'its' from the contraction 'it’s', possessive 'whose' from the contraction 'who’s', and possessive 'their' from 'there' and 'they’re'.
its/it's, whose/who's, their/there/they're
These three homophone groups are among the highest-frequency errors in all English writing — not just in learner corpora. Data from the Corpus of Contemporary American English (COCA) and the British National Corpus (BNC) shows that its/it's confusion is present in a significant proportion of informal digital texts, making it one of the most studied orthographic errors in English. For language learners, the additional challenge is that the possessives (its, whose, their) are structurally similar to each other, while the contractions require recognising elided auxiliary verbs.
its vs it's
Its (no apostrophe) = possessive adjective for things, animals, and organisations:
It's (with apostrophe) = it is / it has (contraction).
The company changed its logo. (possessive — the company's logo)
It's raining outside. (= It is raining)
It's been a long day. (= It has been)
Test: substitute 'it is' or 'it has'. If the sentence still makes sense, write it's. Otherwise, write its.
whose vs who's
Whose = possessive — asking or stating whom something belongs to:
Who's = who is / who has (contraction).
Whose jacket is this? (possessive question)
Who's coming to the party tonight? (= Who is coming)
Who's going to tell the boss? (= Who is going to)
their vs there vs they're
Their = possessive adjective (belonging to them).
There = location or existential ('there is/are').
They're = they are (contraction).
The cinema is over there. (location)
They're going to the concert tonight. (= They are going)
Common Mistakes
✗ Whose going to tell the boss? → ✓ Who's going to tell the boss?
✗ Their going to the concert. → ✓ They're going to the concert.
✗ I hope there friends save seats. → ✓ I hope their friends save seats.