is it piece of mind or peace of mind
Peace of mind is a state of mental and emotional calmness, with no worries, fears or stress. In this state, the mind is quiet, and you experience a sense of happiness and freedom. Such peaceful moments are not so rare. You have experienced them in the past, at times when you were engaged in some kind of an absorbing or interesting activity. Here are a few examples: Watching an entertaining movie or TV program.