Memorize that sentence. If you can’t memorize, have it tattooed on your arm so you never forget the difference in their, there and they’re.
Mixing up those words is the most shit-kicking error a writer can make, and immediately brands the individual as someone not to be trusted, confided in, or spoken to except when absolutely necessary.
This mistake will make you look like a hick, a buffoon, a basement blogger in a bathrobe drinking beer at 8 in the morning who is not a basement blogger drinking beer at 8 in the morning who also happens to be a laid-off copy editor.
There – a place, which means it’s a noun.
Their – possessive, which means it’s an adjective.
They’re – They are – which means it’s a verb. The apostrophe is the tip-off.
Their it is. See how awful that looks? Don’t let this happen to you.