According to me the major cause for anger is expectation. We all expect from others according to our thought and everybody should say ok to our thoughts and if there is a controversy or counter word, our blood pressure get hiked and leads to anger in us. In some times, the dejection also leads to anger. For all such things, we should think both sides when we plan somethings to avoid or expect the controversy. When our thoughts are in the correct way, the others also agreed to our thoughts and we can avoid anger in us. However, we got angry, we should try to passive ourselves by saying one,two,three in our mind (this suggestion told by my grand father in my childhood) otherwise we can swallow a tumblerfull water fastly.