There, they're, and their may sound the same, but we shouldn't use them interchangeably.
- There can be a noun, pronoun, adjective, or adverb. It means "that location."
- They're is a contraction for they are. They is a pronoun and are is a linking verb.
- Their is a possessive pronoun (also an adjective).
They're still over there picking their noses.
In case you get confused like I do, A homonym is a word that sounds the same but has a different meaning. A homophone is a type of homonym. It sounds the same but has a different spelling. There, they're and their are both homonyms and homophones.