To: preposition. "We are going to town."
Too: adverb. "I want to go too!"
Two: number. "We'll go to two shops."
Your: belonging to you. "It's your decision."
You're: Contraction of you and are. "You're making a good choice."
Their: Belonging to them. "It's their game."
There: A place. "It's over there!"
They're: Contraction of they and are. "They're all over the place!