Anger is a normal response; a tool for survival. It can be powerful and a force to achieve if you are able to use it in a controlled and calm way. However, I have worked with many people who are angry inappropriately or uncontrollably. I understand that this can be scary for the angry person, as well as those around them.
Anger is usually attached to something else; perhaps other feelings that the angry person finds difficult to express, such as grief, and pain, so we work together to find those and bring them to the fore. Authentic acknowledgement of these feelings, in safe surroundings, usually enables a greater sense of calm and a capacity to learn to deal with these feelings in a safer way.
“Everything that irritates us about others can lead us to an understanding of ourselves.” Carl Jung