What's the difference between There, Their and They're?

source: Learn English with Let's Talk    2014年11月29日
A most common mistake what students make is the difference between There, Their and They're in written English. This happens because these words sound the same when they are spoken. These Words sound the same but have different meanings and spellings. Therefore the words they're, their and there are Homophones. What is the difference between There, Their and They're?

THERE
There is the opposite of Here. It means “in that place” not here.
A: Where is my book? – B: It’s over there.
I will look for a hotel to stay when I arrive there.
There is/There are = to show that something exists.
There is a book on the table
There are many countries in Europe.

THEIR
Their is a possessive adjective which is used before a noun. It shows possession, that something belongs to them.
Their house is big.
All of their friends were crazy.
The children put their books in their school bags.

THEY’RE
They’re is a contraction of they are.
e.g. They’re happy = They are happy
They’re is usually before an adjective or a verb ending in ING.
They’re very interested in the project.
I personally think they’re crazy!
They’re singing loudly.