Anger is an emotion which is displayed as strong feeling of annoyance, hostility or displeasure towards oneself, someone else or something.
There are various reasons/causes of anger:
Counselling can help with looking at the causes for your anger and making you aware of where it comes from e.g. road rage is usually more about displaced and disproportionate anger which has built up over a period of time, than it is to the actual incident of road rage. It could be more about the feeling of dismissal rather than the fact that someone 'cut you up' on a roundabout.
Further guidance and help can be found at NHS – Anger Management.