Anger is a natural response to feeling attacked, injured or violated. It's part of being human; it's energy seeking expression. Our anger can be our friend. It helps us survive, giving us the strength to fight back or run away when attacked or faced with injustice. In itself, it's neither good nor bad, but it can be frightening.
Angry feelings can lead to destructive and violent behaviour, and so we tend to be frightened of anger. The way we are brought up, and our cultural background, will very much influence how we feel about expressing anger.
You may have been punished for expressing it when you were small, or you may have witnessed your parents' or other adults' anger when it was out of control, destructive and terrifying. Or you may have been frightened by the strength of your own bad temper. All of this encourages you to suppress your anger.
When something makes you angry, you feel excitement in your body and emotions. Your glands are pumping your blood full of the hormone adrenalin, preparing for fight or flight. You are full of energy, alert, ready for action. Tension builds up, but is released when you express your anger. The release is good for you, helping to keep body and mind in balance and able to face life's challenges.