So, I've noticed a few people misusing some words. Me being the grammar nut I am, I've decided to make a guide.
Your and you're.
A mistake that people can make is when they should be using the word you're, they use your instead. Your is showing possessive and you're is a conjunction of 'you' and 'are', so it doesn't make sense to say something like "Your nice." In a situation like that, you would say, "You're nice." You would use your when talking about something that belongs to someone, like saying "That is your bike." A sentence with all of the words used in it would be "You're good at riding your bike."
There, Their, and They're.
There shows a direction, so it would be used in a sentence like this: "The cat is over there." Their, like your, shows possessive, and would be used like this: "That is their cat." They're is a conjunction of 'they' and 'are', and would be used like this: "They're getting the cat." A sentence with all of the words in it would be "They're getting their cat from over there."
I hope this helps, and if there's anything that someone would like me to add, I'd be happy to add it.