Happiness is a state of mind or feeling characterized by contentment, love, satisfaction, pleasure, or joy.

Human relationships are consistently found to be the most important correlation with human happiness.

Aging and happiness

Research in the US has found that older Americans are generally happier than younger adults. The effect does not appear to be generational, because longitudinal research found that happiness increased over time for the older people who were studied. While older individuals reported more health problems, they reported fewer problems overall. Young adults reported more anger, anxiety, depression, financial problems, troubled relationships and career stress.Studies are contradictory as to whether parents are more likely to report being happier than non-parents. One study found having up to three children increased happiness among married couples, but not among other groups with children.

Happiness is also correlated with the ability to "rationalize or explain" social and economic inequalities.

One American study found that people were happier after spending money on experiences, rather than physical things.

Envy is believed to produce unhappiness.

There is now extensive research suggesting that religious people are happier and less stressed.
It is not clear, however, whether this is because of the social contact and support that result from religious activities, the greater likelihood of behaviors related to good health (such as less substance abuse), indirect forms of psychological and social activity such as optimism and volunteering, psychological factors such as "reason for being," learned coping strategies that enhance one's ability to deal with stress, or some combination of these and/or other factors.