Alternative rock is a category of rock music that emerged from the independent music underground of the 1970s and became widely popular in the 1990s. "Alternative" refers to the genre's distinction from mainstream or commercial rock or pop music. The term's original meaning was broader, referring to a generation of musicians unified by their collective debt to either the musical style or simply the independent, DIY ethos of punk rock, which in the late 1970s laid the groundwork for alternative music.