instruction: What is alternative rock?
context: Alternative rock (also known as alternative music, alt-rock, or simply alternative) 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 musicians influenced by the musical style or independent, DIY ethos of late-1970s punk rock.Traditionally, alternative rock varied in terms of its sound, social context, and regional roots. Throughout the 1980s, magazines and zines, college radio airplay, and word of mouth had increased the prominence and highlighted the diversity of alternative rock's distinct styles (and music scenes), such as noise pop, indie rock, grunge, and shoegaze. In September 1988, Billboard introduced "alternative" into their charting system to reflect the rise of the format across radio stations in the United States by stations like KROQ-FM in Los Angeles and WDRE-FM in New York, which were playing music from more underground, independent, and non-commercial rock artists.
response: Alternate rock is a form of rock music popularized in the early 1990s. It was formed to distinguish itself as an "Alternative" to commercial rock and pop music. Artists that fell into this category were more underground and had smaller independent record labels. Most artists were first heard on college radio stations or by word of mouth. In 1988, the genre was officially used by Billboard to accurately chart the rise of this new style being played by radio stations.