My harry potter alter ego???

Wht the hell does alter ego mean??? guys help me out here.....

Harry Potter 75% Ron Weasley 65% Ginny Weasley 60% Sirius Black 55% Hermione Granger 50% Remus Lupin 50% Albus Dumbledore 50% Lord Voldemort 45% Draco Malfoy 45% Severus Snape 45% You scored as Harry Potter. You can be a little reckless and hot-headed at times, but a more brave and courageous friend would be hard to find. Your Harry Potter Alter Ego Is...? created with QuizFarm.com