There” is frequently used as an adverb to indicate “in or at that place.” It is easy to remember it contains the word “here,” which is also a place. For example, “Put the garbage over there.” Another example is “Stop right there.” It is also used as a pronoun when it starts a sentence and comes before the verb (usually a “to be” verb), such as “There are many ways to get to town.” “Their” is a pronoun that shows ownership or possession; it is followed by a noun. For example, “Their dogs ran across the street.” “They’re” is a contraction for “they are”; if you can substitute “they are” in its place, then “they’re” is the correct choice. For example, “They’re (they are) tired from the trip.”

Please note, “there” has other uses, but this serves as a simple presentation to highlight its most common uses for clarity. An easy trick for “there” is to eliminate the other two choices; if you can’t use “their” or “they’re,” then you are safe to go with “there.”There, their, and they're