The World Happiness Report has ranked Finland as the world's happiest country with Nordic neighbours, Denmark, Norway and Iceland runners-up.
Finland has been ranked the world's happiest country for the second year in a row, according to a United Nations report.
The World Happiness Report said that Nordic neighbours Denmark, Norway and Iceland followed shortly behind Finland in the ranking.
Factors used for the assessment include gross domestic product per capita, life expectancy and perceived corruption in government and business.
This year's report had a special focus on "happiness and the community", considering factors such as social media and technology, social norms, conflicts and government policies.
Rounding off the list of the top 10 happiest countries were the Netherlands, Switzerland, Sweden, New Zealand, Canada and Austria.
The United States ranked 19th, Russia 68th, China 93rd, and India 140th.
"How communities interact with each other whether in schools, workplaces, neighbourhoods or on social media has profound effects on world happiness," said John Helliwell, a professor at the University of British Columbia and co-editor of the report.
Trailing the World Happiness list were Rwanda, Tanzania, Afghanistan, the Central African Republic, and South Sudan.
The report, commissioned by the United Nations Sustainable Development Solutions Network, was released in conjunction with the World Happiness Day.
The 10 most happy:
5. The Netherlands
8. New Zealand
The 10 least happy:
155. Central African Republic
156. South Sudan