You’re, Your

I often enough see your used where you’re should be used.

You’re is the contraction for you are.

Take the following sentence: You’re your own worst enemy. You’re (you are) your own worst enemy.

Your shows possession just like my, his, her, its, their (your worst enemy, his worst enemy, their worst enemy, etc.).

Sherry

Paul’s book–Literally, the Best Language Book Ever;

Sherry’s Grammar List