Their vs There vs They're: which is correct?

One spelling, one job

The cleanest way to master this trio is to give each spelling a single job and refuse to let it do any other. Their is the possessive: it always shows that something belongs to them. Their car, their opinion, their turn. If you can replace the word with our or my and the sentence still works grammatically, you want their, because it sits in the same possessive slot.

There is about place or existence. In its place sense it is the opposite of here: put it there, the keys are over there, look there. In its existence sense it introduces a statement that something exists: there is a problem, there are four options, there seems to be a delay. A handy clue is that there contains the word here, and both are about location. Whenever the word points somewhere or kicks off a there is or there are phrase, it is there.

They're is the contraction of they are, and nothing else. They're late, they're my neighbours, they're going to win. If you can expand the word to they are and keep the sense, the apostrophe version is correct. That expansion test is the single most reliable check of the three.

Three quick tests in order

Run them in sequence and you will never miss. First, try expanding to they are. If the sentence survives, write they're and stop. They're here for dinner becomes they are here for dinner, which works, so they're is right. This is the easiest test, so do it first to clear the contraction out of the way.

Second, if they are does not fit, ask whether the word points to a place or introduces an existence statement (there is, there are, there seems). If yes, write there. The cafe is just there, and there is no rush, both pass this test. Remember the here inside there as your reminder that this one is about location.

Third, if neither of the first two tests fits, the word is showing possession, so write their. By elimination, anything that is not they are and not a place or existence word is the possessive their. They lost their tickets is not they are tickets and not a place, so it is their. Working through the three tests in this order turns a three-way guess into a short checklist.

Examples that use all three

Watch the three do their separate jobs in one passage: they're going to leave their bikes there overnight. They're is they are, their marks the bikes as belonging to them, and there points to the place the bikes will stay. Three identical sounds, three different spellings, each earning its place.

Another: there are people who never lock their doors, and they're usually fine. There introduces the existence statement there are, their shows the doors belong to those people, and they're expands to they are usually fine. If you can parse a sentence like this confidently, you have the distinction.

Common real-world slips cluster in fast writing: their is most often miswritten as there, and they're is dropped in favour of either of the others. Because all three are valid words, spell-check cannot catch the swap, so the tests have to be yours.

Locking it in

Mnemonics help here more than with most pairs. There has here in it, so it is the one about place. They're has an apostrophe standing in for the missing a in are, so it is the contraction. Their is left over for possession, and it is worth noting that their contains heir, someone who owns or inherits something, which nudges it toward the ownership meaning.

When you proofread, hunt down every instance of any of the three and run the ordered tests: they are first, place-or-existence second, possession by default. The whole check takes a couple of seconds per word and is completely unambiguous. Practise on the quiz above, mixing all three, until each spelling triggers its job automatically. Of all the confusable sets in English, this is the one that rewards the test-as-you-write habit most, because three homophones give error three chances to slip in.