What Guys Said 2
He is trying to impress you and show off (big ego) or is insecure and trying to feel accepted
He thinks your interesting, he is not sure if you know about him so he's telling you about himself, if you react positively. Also he may think if he tells you about himself you'd tell him about you. This doesn't mean romantic feelings, he wants to make friends.
What Girls Said 2
the guys into you will dig for a lot information about you instead of just talking about himself