Underground Rock Music
Experimental & Indiependent
Underground genres is group of musical genres. There are many independent rock genres like indie rock, shoegazing, math rock, emo, twinkle, post rock, mathcore, etc.
Independent music (also called "indie") is free, certanly independent music. There are some indie genres, for example, 'tis indie rock, shoegazing, emo, post-hardcore.
Shoegazing (also known as shoegaze) is a subgenre of alternative rock.The shoegazing sound is typified by significant use of guitar effects, and indistinguishable vocal melodies that blend into the creative noise of the guitars.
Indie rock is just free underground music.
Avant-garde rock, also known as Experimental rock, is a type of music based on rock which experiments with the basic elements of the genre.
Post-rock is a subgenre of rock music characterized by the influence and use of instruments commonly associated with rock, but using rhythms and "guitars as facilitators of timbre and textures" not traditionally found in rock.The next stage in the development of post-rock is math rock.
Math rock is a rhythmically complex, often guitar-based, style of experimental rock and indie rock music, influenced by progressive rock bands. It is characterized by complex, atypical rhythmic structures, counterpoint, odd time signatures, angular melodies, and extended, often dissonant, chords.
Mathcore is a rhythmically complex and dissonant style of metalcore. Math rock groups such as Slint, Don Caballero, Shellac, and Drive Like Jehu have some influence on mathcore, though mathcore is more closely related to metalcore. Prominent mathcore groups have been associated with grindcore.