This is for everyone who hasn't taken the time to internalize basic rules of American-English grammar.
"You're" is a contraction for "you are." "Your" is a possessive pronoun that attributes ownership to a single person of address.
"Their" is the plural possessive form of "his" and "hers." "They're" is a contraction for "they are." "There" is an adverb, noun, pronoun, adjective, or interjection, depending on its use. It usually refers to a specific location, either literally or within a statement or idea.
"It's" is a contraction for "it is." "Its" is a possessive pronoun.