Whilst Punk was revolutionary in terms of it’s socio-political statement, it wasn’t actually all that innovative musically. Three chords, three-minute songs and freedom to say what the f*ck you want isn’t actually that advanced a musicological concept. Luckily, there were plenty of artists who really wanted to be artists and not just some kind of shock factor, and it was two of Punk rocks leading lights, John Lydon of the Sex Pistols and Howard Devoto of the Buzzcocks who went on to form Public Image Ltd. and Magazine respectively, two projects that would both prove to be considerably more advanced in a musical sense than anything they’d written before.
The Manchester based Punk band "Warsaw" became Joy Division, developed unique styles of bass guitar, vocal performance and drum recording and thus became the short-lived musical legends that everyone now knows they became. They plus Siouxsie & the Banshees, Bauhaus and Killing Joke laid down between them the foundations for the Gothic music genre, which became "the sulky daughter of Punk".
Most of the early Industrial and Synthpop bands could also be classified under the "Post Punk" banner. Other musical influences could be welded onto Punk to form a new variant of "Post Punk", these could well be Dub Reggae, Ska, and Funk, Kraftwerk inspired robobleep, in fact, many artists blended anything that seemed like a good idea at the time, into Punk, which has still got to be the true do what you want and F*ck the consequences attitude of Punk. Whether it still seems like a good idea now is a matter up for debate, but suffice to say "Post Punk" has given the world a rich and varied backcatalogue.
Whilst many of the best known "Post Punk" bands originated from the UK, the Americans weren’t left behind. The town of Akron, Ohio provided us with Pere Ubu and Devo, Boston delivered "Mission Of Burma" and there was also the entire New York ‘No Wave’ scene that was essentially a genre on it’s own. Other national scenes existed – the opening phase of the French Coldwave and the first (experimental) phase of the Neue Deutsche Welle both ran more-or-less parallel to "Post Punk".
The "Post Punk" movement eventually became buried under the genres that it inspired – whilst music that was in some way inspired by the original Punk aesthetic never really went away, the term "Post Punk" itself went on a two decade-long hiatus. The umbrella term New Wave continued to hover over a number of the more commercially viable (i.e. less weird) "Post Punk" bands, but like everything else that is deemed ‘new’, the term died out when it wasn’t new any more.
It would reappear in the early 00s, when a significant number of bands began name checking the likes of U2, Gang Of Four" and Joy Division – the "Post Punk" revival (or was it more of a New Wave revival?) was in full swing, and didn’t the record industry love it – a fresh wave of guitar Rock bands that would appeal to the disposable-income laden adult Rock consumer, plus a renewed interest in a substantial chunk of their backcatalogues!
Plus all the No Wave acts tearing up New York at the time.