pop punk
Examples: 

- Blink 182 (their old stuff is punk, everything from their first album onwards is crap)
- New Found Glory
- Good Charlotte
- Simple Plan
- All-American Rejects

among many others.
People call bands like these "pop punk", when in reality, they're mostly just pop with a very slight punk-like sound.

Also, some would call Avril Lavigne pop punk, when in reality, she doesn't even remotely sound like punk at all. She does, however, "dress punk", to the annoyance of those who do listen to punk.
True "pop punk" is actually punk with a slightly softer sound and more melody, such as Millencolin, Dillinger Four, etc, NOT Blink 182...