What exactly is happiness? Can we measure it? Why are some people happy and others not? And is there a drug that could eliminate all unhappiness? People all over the world, and throughout the ages, have thought about happiness, argued about its nature, and, most of all, desired it. But why do we have such a strong instinct to pursue happiness? And if happiness is good in itself, why haven't we simply evolved to be happier? Daniel Nettle uses the results of the latest psychological studies to ask what makes people happy and unhappy, what happiness really is, and to examine our urge to achieve it. Along the way we look at brain systems, at mind-altering drugs, and how happiness is now marketed to us as a commodity. Nettle concludes that while it may be unrealistic to expect lasting happiness, our evolved tendency to seek happiness drives us to achieve much that is worthwhile in itself. What is more, it seems to be not your particular circumstances that define whether you are happy so much as your attitude towards life. Happiness gives us the latest scientific insights into the nature of our feelings of well-being, and what these imply for how we might live our lives.