I have included all types of sound files beacuse you can dowload the software to play any format for free if you don't already have it. Some songs even have informative blurbs after them.I figured kids wouldn't listen to such god awful bands as Madball and One Life Crew if you gave them a chance to hear good music for free. All of this stuff is linked, because it's stuff I have found all over the web, and thought it would be cool if you could reference the sounds I have spent a long time looking for all in one place.