Answer: Modern psychology describes anger as one of the emotional reactions of the fundamental instinct of self-preservation. When the question self-preservation comes a creature reacts either by fight or flight. When it is fight, anger is the prompting emotional reaction. When it is flight, fear is the prompting emotion.
So anger is basic to human nature, as also sexuality and greed for possession. But if man gives free rein to them, he will be reduced to animality.
Generally anger comes when one feels that one has been insulted or injured or in any way harmed by another. These feelings are Vrittis, or modes or waves coming in the mind. Generally when these feelings come we identify ourselves with it, and forget all good sense. They are just like clouds coming over the clear sky. When the cloud comes, the sky looks all dark, though really it is clear. If you train yourself to look at these feelings in a detached way when they overtake your mind, you will be able to establish over them gradually.
In daily life man can exercise control over anger if he observes a few practices. When anger is roused, he should not react by speaking. He should keep quiet, and either repeat the name of God or discriminate.