A Pretty good type of music that most "Real" punks look down upon just because it doesent live up to Punks standards. And yes, I agree with them. Most pop punk is a pile of shit. But there is alot of really good Pop Punk out there that is Loud, fast, fun and rebelious. But it is basicly just a more melodic and catchier type of punk rock.
Good Pop Punk: Descendents, NOFX, (old) Green Day, Lagwagon, Screeching Weasal, (Old) Blink 182, Ramones, The Offspring, (Old) Mxpx, Rancid, The Buzzcocks, The Sidekicks, etc
Bull Shit Pop punk: Simple Plan, Paramore, Fall out boy, We the Kings, Boys like Girls, (New) Blink 182, New found glory, good charlotte, Avril Lavigne, Sum 41, etc