The trio of their, there, and they’re can flummox writers at all levels. The confusion stemming from these words is that even though they sound the same, writing them down correctly is a different story! Here’s a simple way to remember the differences between the three.
THEIR has the word ‘heir’ in it, so that particular spelling indicates ownership and is generally plural, e.g. they left their keys on the table.
THERE has the word ‘here’ in it, so then you are talking about places or ‘that place’, e.g. She went there yesterday. There is also used as a pronoun to introduce a phrase or sentence, e.g. There is still time left.
THEY’RE has an apostrophe (which is another issue altogether – look out for my next tip pointing out the pitfalls of the apostrophe!) which is a contraction of the words they and are, e.g. They’re going on holiday.