You're in Your Prime (you're and your)

Two words that are frequently confused are "your" and "you're."

The first one is possessive and refers to something that belongs to you. You'll remember it better if you notice that "our," another possessive, is inside it.     
YOUR  attendance is required.


The second one is called a contraction, or a "pulling together" of the two words "you are."  
YOU'RE required to attend.

Imagine the two words joined as "youare;" then remove the "a" and replace it with an apostrophe. Keep in mind that the apostrophe is taking the place of the missing "a."  Remember that, with personal pronouns (I, you, he, she, it, we, they), an apostrophe does not show ownership as it does with nouns.

I just heard that YOU'RE going to Hawaii for YOUR vacation. (You are going, and you own the vacation.)