English Grammar Rules & Mistakes: Learn All of the Essentials: Writing, Speaking, Literature and Punctuation Rules Complete with 10 Key Skills and Over 200 Common Error Examples

Homophones - the same sound with a different spelling
There is only really one example that we need to talk about when we go
through what a homophone is (don’t worry, we will actually go through
three!) As soon as I mention it, you will know what I am referring to. A
homophone is a group of words that all sound the same but have a different
spelling. They also represent the most repeated mistake that a native speaker
of English will make when writing. Let’s see that first example now so we
can all get on the same page.
You’re behaving exactly like your brother, naughty and rude!
The misuse of your and you’re is widespread among all native speakers of
English. Are you guilty of it? Don’t worry if you are, we will fix it now. So
to be very clear, you’re is a contracted version of the two words ‘you are’.
Your is a possessive word that means something belongs to you, in this case,
it is your brother.
What most people do who confuse the meaning of these two homophones, is
use only your in all circumstances. 
Your very welcome!
I am sure you have seen this common mistake, perhaps someone has
ridiculed you for making it yourself. To make sure that you don’t make it
again when writing, slow down a bit and think about what it is you are trying
to say. You are very welcome is the correct and full version of this sentence.
If you want to shorten it, you can to you’re. My advice though, if you don’t
want to mess up while writing, use the full version every time.

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Their new house is over there and they’re really pleased to be in this
neighborhood.
Very similarly to the previous example, many people trip up over this
homophone. Let’s clear it up together. Their is a possessive word and means
that something is theirs. It will always have a noun after it, in this case, it is
their new house. There is a location word meaning that over there. They’re
is a contracted word meaning they are. Just like before, if you don’t know
which version to use, slow down and think of the meaning. If you can avoid
using they’re you will also find that you don’t fall in the trap that it has laid
for you.