underground rap

so i talked a little bit about underground rap and what it is and how it effects hiphop. its the rap that doesnt get the same hype as mainstream rap because the rapper refuses to sell out. its supposed to be better and show us the morals that we are losing in are new music we hear on the radio. ive heard people say its just the radio that keeps it underground because its hard to get a radio spot. when will we get more clarity on what underground hiphop is. when will the mainstream wanna know as much as i do.