What is anger?

Maybe it is obvious, but I've been thinking about anger lately and am wondering what it is, exactly.  For one, we could say that anger is an emotion.  And that would be true.  But what is going on with it?  I'm thinking that anger is usually a response to a situation that we believe to be wrong or contrary to what we want.
Along the same lines, why is it that we are now seeing anger so prevalent in music?  Looking back over the centuries, I cannot identify any music that expressed anger.  All of the classical genres and all of the folk music, from the various cultures, does not express anger but instead, usually, joy, fun, or grief.  I wonder why this is. 
I don't believe our culture is really any different than multiple cultures in the past.  We have the same kind of sins and inclinations as everyone else.  Why is angry so prevalent now?  Have we become so self centered that we only think of ourselves and what we want?  One variable that we have, that other cultures have not had, is electronic technology.  This does allow us to focus on our own little world, of our own creation.
The Orthodox worldview calls for the living out of one's faith within a community.  This is centered on loving others.  Could it be that technology is drawing us away from life in a community?