In the 1960s, the term underground was associated with the hippie counterculture of young people who had dropped out of college and their middle class life to live in an off-the-grid commune of free love and cannabis. In modern popular music, the term “underground” refers to a performers or bands ranging from artists that do DIY "guerrilla concerts" and self-recorded shows to those that are signed to small independent labels. In some musical styles, the term “underground” is used to assert that the content of the music is illegal or controversial, as in the case of early 1990s death metal bands in the US.

Shlomo Sher's "philosophy for artists" argues that there are three common misconceptions about the "underground": that it refers exclusively to the rave/electronica scene; that it can be described with a vague, broad definition of "anything which is not mainstream"; and the myth that underground music is kept secret; he points out that no band or performer "exclud[es] virtually anyone or anything" using "secret passwords and hidden map points". Instead, Sher claims that "underground music" is linked by shared values, such as a valuing of grassroots "reality" over music with "pre-wrapped marketing glossing it up"; sincerity and intimacy; freedom of creative expression is valued over commercial success; art is appreciated as deeply meaningful fashion; and the Underground "difficult to find", because the scene hides itself from "less committed visitors" who would trivialize the music and culture.

In a Counterpunch magazine article, Twiin argues that "Underground music is free media", because by working "independently, you can say anything in your music" and be free of corporate censorship. The genre of post-punk is often considered a "catchall category for underground, indie, or lo-fi guitar rock" bands which "initially avoided major record labels in the pursuit of artistic freedom, and out of an 'us against them' stance towards the corporate rock world", spreading "west over college station airwaves, small clubs, fanzines, and independent record stores." Underground music of this type is often promoted through word-of-mouth or by community radio DJs. In the early underground scenes, such as the Grateful Dead jam band fan scenes or the 1970s punk scenes, crude home-made tapes were traded (in the case of Deadheads) or sold from the stage or from the trunk of a car (in the punk scene). In the 2000s, underground music became easier to distribute, using streaming audio and podcasts  Punk rock was an underground musical form when it first developed in the mid-1970s, as was its descendant,UK 82-style hardcore. UK hardcore bands from the early 1980s such as Discharge eschewed major labels.

Even some musical styles that eventually became mainstream, commercialized pop styles started out as underground music. Late 1970s disco is often considered to be a very commercialized type of pop music. However, before disco's mainstream adoption in 1977 and 1978, disco records were underground music created by nightclub DJs for the gay dance club scene. Similarly, hip hop began "on the streets"; in the early 1980s, rappers did beatboxing and made up rhymes for tiny underground labels. Genres such as alternative rock, grunge, various forms of heavy metal, grindcore, electronica, outsider music, and experimental music, also trace their roots to underground scenes.

A music underground can also refer to the culture of underground music in a city and its accompanying performance venues. The Kitchen is an example of what was an important New York City underground music venue in the 1960s and 1970s. CBGB's [5] is another famous New York City underground music venue claiming to be "Home of Underground Rock since 1973".

Source: Underground music - Wikipedia, the free encyclopedia