How Are Songs for "Bad Meets Evil" by Eminem Already Being Released?

I heard of the album first when i was on xbox and i thought it was cool. So i went online on youtube and searched it; and all of the track list and the songs are there. Some (most) even have download links already. So how are the songs already being released to the public if the album hasn't even officially come out yet? Why would the record company do this, wouldn't it ruin the point of selling albums? And is there any copyright issues affiliated with the downloads? Please give a somewhat detailed answer because 2 words don't describe it good enough for me lol thanks!