Now, there there. *pat pat*

There are few things that get on my nerves more than seeing text messages or, worse, fan fiction, wherein the author has little-to-no understanding of how to use these nifty little words. They aren't even in the same part of speech!

But, I digress. See below for an explanation of these three frustrating words.

This word is a pronoun. It is used to convey ownership. Below is proper usage of the word "their".

• Bob and Sally like their car.

This word is a contraction of the words "they" and "are". If you're having trouble deciding which of the three options to use, substitute "they are" for the word, and if the sentence still makes sense, you're probably on the right track.

• They're going to the movies tomorrow.

This word is an adverb. As such, it is used to modify where a verb is taking place. Where are they building that new house? Over there.

• There are many rules in the english language.
  

• Their son called to tell us that they're going to be there soon.
• Over there they're planning to build their new house.
• They're looking for their missing plane tickets over there.

These sentences, of course, are only proper if "their", a pronoun, is defined in a previous sentence.

Also, keep in mind that these three are homonyms.

For more information about using pronouns properly, see the link to my article discussing the eight parts of speech, below.

For more information about homonyms and using them properly, see the link to my article discussing homonyms and homophones, below.