The United Nations is marking the International Day of Happiness by asking people to nominate a song that makes them smile.
UN Secretary Ban Ki-Moon launched the campaign with a music video of his own.
The idea is to recognise that contentment and well-being should not just be personal goals but public policy objectives.
The video has been released in six different languages.
Ban Ki-moon on #HappyDay: #HappySoundsLike peace & prosperity for all. https://t.co/wJ8IWSFUal #UN70 #Action2015— United Nations (@UN) March 19, 2015
The UN has asked organisations and individuals to observe the day through education and public awareness activities.
It says people can take part through Twitter by sharing their happiest song #HappySoundsLike.