They're vs. There vs. Their
They're is the contracted form of They are. This form is used in sentences using "they" as the subject of the sentence with the verb "to be" used as either the helping verb (e.g. They're going ..., They're playing ...) or the principal verb of the sentence.
They're working hard this week.
They're very interested in helping out.
There is used as an introductory subject is sentences with "There is" and "There are". It is also used as an adverb of place meaning "in that place".
There are many people in that room.
That's my house over there.
Their is the possessive pronoun form. This form is used to express that "they" have a specific quality, or that something belongs to "them".
Their house is in Los Angeles.
He liked their looks!
Do you understand the rules? Test your knowledge with this they're vs. their vs. there quiz.