Happiness plays essential role on building prosperity and success in any society. Happiness is one of the essential factors to reach prosperity and success in people’s life and jobs but happiness is not always the same as capability, but they may be correlated while capability is a necessary for having a happy life and happiness feeds back on capability in different ways. People who feel happy could better contribute to society and help other people build better future. This study performs a review on recently completed studies on factors, which influence happiness, new definitions of happiness. The study concentrates more on empirical investigations on the concept of happiness.