Three words often confused are the homonyms there, their, and they’re.

Their is a possessive adjective. It always precedes a noun and indicates possession:

That cabin is their country residence.

They’re is a contraction of the words “they are”:

They’re interested in buying your house.

There has more than one function. It is used as an adverb of place:

See that Victorian house? I lived there when I was nine.

There is used as a sentence opener:

There are fishes in the pond.

Note: Beginning a sentence with there is sometimes the correct stylistic choice, but a common error is to begin a sentence with there when beginning with a subject would be better. For example:

Weak: There will be a brass band to meet the war hero at the airport.
Better: A brass band will meet the war hero at the airport.

Weak: There are plenty of reasons for her to refuse his advice.
Better: She has plenty of reasons to refuse his advice.

Courtesy: Daily Writing Tips