Rooted in garage rock and other forms of what is now known as protopunk music, punk rock bands eschewed the perceived excesses of mainstream 1970s rock. They created fast, hard-edged music, typically with short songs, stripped-down instrumentation, and often political, anti-establishment lyrics. Punk embraces a DIY (do it yourself) ethic, with many bands self-producing their recordings and distributing them through informal channels. The ideals associated with punk music have caused a rift between fans of the music due to mainstream bands claiming the title while not applying any of the characteristics aside from instrumental simplicity.
However before the UK '82 and US Hardcore styles emerged, and with them certain "uniforms" and unifying culture, punk was less of an aesthetically homogenous style and more of an umbrella movement where uniqueness and self-expression were encouraged. Examples of this are the original New York punk bands associated with CBGBs who had very little in common stylistically, and also the bands involved in the UK scene who used elements of reggae or goth in their music (in fact it was from this post-punk scene that goth eventually emerged). Therefore it is arguable that any band rooted in punk yet creating their own sound against expectations are more in the spirit of true punk than a band sticking rigidly to the genre blueprints.