Okay so me and my sister are getting college letters and emails and.......?

How did they get our home address and emails? I mean, although its pretty cool, I'm just wondering how they got our info. Apparently its all coming from the college board or something or from our PSATs or something like that. But I'm still kind of unsure. But I mean I'm getting a ton from all sorts of places. I don't know whether or not to take it all seriously