When people are called punks or call themselves punks, it is usually seen as a description of their physical persona or dress; rarely is it acknowledged that there is a mental and intellectual attitude that sets them apart.
Punk is a mentality, but it isn't a consistent mentality. It's an attitude, but not all punks share the same attitude. It is easily represented by one who doesn't swallow outright what people tell them, yet they don't all think the same things.
Punks are as varied as the kid who goes to school with the 8 inch long mohawk, to the plainly dressed 30-year old who quietly attends political rallies, the girl with the green hair and body piercings, the 70 year old next door neighbor who refuses to let the police tell him that he needs to mow his lawn because it is "unsightly", and the single mother who holds her own with two jobs and still finds time to read both the local newspaper and Z Magazine.
Punk is whatever you want to make it. That's the beauty of "punk". It is being yourself, not someone else.
Most people, having heard that, would assume that everyone is punk, since everyone is their own person, of course. Yet, the majority of people in the world, for better or worse, follow the decisions, dress, attitudes, lifestyles, thoughts, ideologies, and actions of everyone else around them, without question.
"Punk" simply means you question things.
"... punk rock is just a self help manual for those who see themselves as rebels." -- Rachel of Red Monkey
Decent starting points for punk rock music
Bad Brains - "Black Dots" or s/t The most dangerous band playing the most dangerous music. Revolutionary. Bad Religion - "All Ages Intellectualized punk with a philosophical twist and anti-authoritarian agenda. Bikini Kill - "Pussy Whipped" The best introduction to radical sexual politics I could've ever asked for. CRASS - "Best Before 1984" This collective attacks the entire British power structure and manages to get erased from the UK's official music history. Dead Kennedys - "Fresh Fruit for Rotting Vegetables Sarcastic and bitting, this album ridicules everyone in sight from the early 1980's. Minor Threat - "Complete Discography Fast as hell and aggressively angry. Minutemen - "Double Nickels on the Dime" Eclectic and poetic, this record says amazing things. Propagandhi - "Less Talk, More Rock" Quite easily the most political album ever made... teeming with propaganda.