Somebody that listens to all the genres of rock music, knows how to play a rock instrument (keyboards, piano, drums, guitar, bass, you know whats a rock instrument and whats not) or sing.
A true rocker doesnt listen to music of any kind unless it is rock or unless its a combination of rock and something else.
They wear stuff like studs, bullets, spikes, combat boots, shoes, jeans, band t shirts , leather gloves, camo pants, etc.
You never know what kind of hair a rocker may have. It could be an emo fringe (and yes, emo is a genre of rock) or it could be a mohawk. It can be long or short. Really it doesnt matter all that much.
Some wear black nail polish and eyeliner.
Some of you might say that this is a label, it could be, but really it is just a way of life.
There are rock subcultures of many types like goths, punks, emos, indies, metalheads etc. or they are simply rockers. But this is really my opinion on what a true rocker really is. The majority of rockers will find there selves with hip hop people like rappers, r&b people, reggaetons, etc. Mostly bc of musical differences.
And to those that dont agree with me you are obviously blind.
Why look at him. He has his guitar, in his hands, and is about to rock out against the rapper. I can tell he is probably a true rocker.