Most times, we are surprised at the rate at which people express anger especially over trivial matters and we start to wonder if what happened was all there is or there are other details we're not aware regarding the matter. Well, most times what a person express might be as a result of accumulated frustration mostly transfer of aggression that might have resulted from economic hardship, injustice and discrimination etc Also, it might be as a result of environmental factors such as being raised in a hostile environment where your parents tempers usually flare over trivial matters, as you grow older, you are more likely to respond to life's problems with anger...
All you made mention are the cause but there are some ways we could deal with anger, if someone did something or said something we find offensive and we know there's no way we could hold back, the best thing is to keep shut and leave that place because if we do not, the more the person keeps doing whatever he's doing to offend us it will make us to talk, react. For me trying to gain control is the only way, if we allow anger to control us then it will be too hard to hide how angry we are, this isn't a day something and we must be alert whenever something we know would make us angry is approaching, avoiding it keeps us far from getting angry easily.
Even great scholars have said that if you cannot control your anger, you will easily lose. People try to make you angry by talking against you because in anger you say things that will later be used against you. Some people often try to make themselves look superior by insulting others. It is possible to make someone angry by making them do many things that they would never consciously do. And the words that come out of that anger will later be used as a more powerful tool against you.
But if someone does not get angry and remains silent and leaves that place, then later people will have nothing to say against you. They will not be able to use any sarcastic words against you even if they want to. Getting angry is a very natural. But wise people say that if you can control your anger, you have acquired the power to control the entire world.