Is Area 51 hiding aliens?

Okay, so I'm not a physco crazy person who studies "aliens" 24/7. I'm just a curious girl. So what I heard on the history channel was that they found aliens but they didn't tell anybody because the world would react in a crazy mob. Like the movie E.T I guess. This was just a curiousity and I may be wrong. Is Area 51 even studying aliens? Remember, just a curiousity. (: Thank You.