It is defined by its mixture of dissonant noise or feedback with the songcraft more often found in pop music.
"[1] AllMusic cites the Velvet Underground as the earliest roots of the genre, with their experiments with feedback and distortion on their early albums.
[1] Early American alternative rock bands like Sonic Youth, Yo La Tengo, Hüsker Dü, R.E.M., The Replacements and Dinosaur Jr., who mixed pop song structures with extreme guitar distortion and feedback,[2] were immediate forerunners.
The Jesus and Mary Chain's 1985 debut, Psychocandy, is considered by AllMusic to be the archetype for the noise pop genre ("pretty much birthed the style").
[1] Kareem Estefan of Stylus Magazine cited the album for "transforming the use of distortion in indie rock with its screeching abrasion, yet managing to feature some of the catchiest melodies of the 80s.