Emotional experiences perceived as pleasant, such as joy, interest or contentment, contrast with those perceived as unpleasant, like anxiety, sadness, anger, and despair. Happiness, or the state of being happy, is a human emotional condition. The definition of happiness is a common philosophical topic. Some define as experiencing the feeling of positive emotionial affects, while avoiding the negative ones. Others see it as an appraisal of life satisfaction, such as of quality of life. Recent research suggests that being happy might involve experiencing some negative emotions when humans feel they are warranted.