Let us talk contractions and homonyms, shall we?
Contractions are formed by combining two short words into one, adding an apostrophe in order to represent a missing letter or letters.
Contractions serve to make text or speech less formal, and as such are generally not recommended for professional documents. Some people adore contractions, some people do not.
If you are ever in doubt as to whether or not you are using the correct spelling of a frequently-contracted word, simply ask yourself, “should I be using two words here, or one?”
Homonyms are words that are pronounced the same, but spelled differently. They tie in nicely to contractions.
To better illustrate, some examples:
Your and you’re.
Your indicates possession: your chocolate bar, your cats, your insanely frustrating coworker.
You’re is the contraction of you and are: You’re going to the store, or You are going to the store. You’re here! or You are here!
Their, they’re and there
Their indicates possession: their chocolate bars, their cats, their insanely frustrating coworkers. These are the chocolate bars, cats or frustrating coworkers that belong to them.
They’re is a contraction of they and are. They are going to the store, or they’re going to the store. They are really annoying me, or they’re annoying me.
There is a location. I’m going there later. It’s over there. There is the book I wanted!
Its and it’s
Oh my fucking God, people are insanely stupid when it comes to its and it’s. I wish this were for the last time, but alas, here we go:
Its indicates possession. This is my computer, and these are its applications. My apartment floor and its little dust bunnies of cat hair. My cat and its food dishes.
It’s is a contraction of it and is. It’s really annoying that people are dumb about contractions, or It is really annoying that people are really dumb about contractions. It’s almost time to go! or It is almost time to go!
Remember, whenever you’re in doubt — especially over the your/you’re and its/it’s questions — try to use the extended version. If that doesn’t work, it’s not a fucking contraction!