You're vs. Your

You're is shorten from You are. "You" is a subject and "are" is a verb to be (like you're playing..., you're falling...)

Examples :

• You're the nicest person I know.
• You're not going to the zoo with us?

Your is a possessive pronoun form to indicate something belong to you.

Examples :

• That is your cat.
• Your house has been selected as the most beautiful house in the area.