Happiness, gladness or joy is a mental or emotional state of well-being defined by positive or pleasant emotions ranging from contentment to intense joy. A variety of biological, psychological, religious and philosophical approaches have striven to define happiness and identify its sources. Various research groups, including positive psychology, are employing the scientific method to research questions about what "happiness" is, and how it might be attained.
The United Nations declared 20 March the International Day of Happiness to recognize the relevance of happiness and well-being as universal goals.
Philosophers and religious thinkers often define happiness in terms of living a good life, or flourishing, rather than simply as an emotion. Happiness in this sense was used to translate the Greek Eudaimonia, and is still used in virtue ethics. There has been a transition over time from emphasis on the happiness of virtue to the virtue of happiness.
A widely discussed political value expressed in the United States Declaration of Independence of 1776, written by Thomas Jefferson, is the universal right to "the pursuit of happiness."
Happiness is a fuzzy concept and can mean many different things to many people. Part of the challenge of a science of happiness is to identify different concepts of happiness, and where applicable, split them into their components. Related concepts are well-being, quality of life and flourishing. At least one author defines happiness as contentment. Some commentators focus on the difference between the hedonistic tradition of seeking pleasant and avoiding unpleasant experiences, and the eudaimonic tradition of living life in a full and deeply satisfying way.
The 2012 World Happiness Report stated that in subjective well-being measures, the primary distinction is between cognitive life evaluations and emotional reports. Happiness is used in both life evaluation, as in “How happy are you with your life as a whole?”, and in emotional reports, as in “How happy are you now?,” and people seem able to use happiness as appropriate in these verbal contexts. Using these measures, the World Happiness Report identifies the countries with the highest levels of happiness.