Happiness is that feeling that comes over you when you know life is good and you can't help but smile. It's the opposite of sadness.
Happiness is a sense of well-being, joy, or contentment. When people are successful, or safe, or lucky, they feel happiness. The "pursuit of happiness" is something this country is based on, and different people feel happiness for different reasons. Whenever doing something causes happiness, people usually want to do more of it. No one ever complained about feeling too much happiness.