Their and there
Their – of or belonging to them (it shows ownership).
There – is, at or to that place or position (it means “that location”).
To remember the difference:
1. That house is their house.
2. Put your coat down over there.
3. They were on their way to school.
4. There is the hotel we stayed at last year.
“There” is also often used to precede “is”, “was, “are” and “were” in sentences such as:
There are/were many different way of solving the problem.
There is/was a saying that pigs might fly.
There are/were nine million bicycles in Beijing.
Something else that sounds like “there” and “their” is “they’re”.
“They’re” is a contracted (shortened) form of “they are”. Some people make the mistake of writing, for instance, “Their going to the party”, when what they really mean is “They’re (they are) going to the party”.
All together in one sentence
Here’s a single sentence that illustrates the correct use of their, there and they’re:
“Their aunt said there is no doubt they’re walking to the party, and should be there soon.”
Use “they’re” in informal writing; if it’s an essay or other formal writing, use “they are”.