A song may be for a solo singer, a lead singer supported by background singers or larger ensemble involving more voices singing in harmony although the term is generally not used for large classical music vocal forms including opera which use terms such as aria and recitative instead. Muslims believe that Islam is the complete and universal version of a primordial faith that was revealed many times before through prophets including Adam, Abraham, Moses and Jesus and the Quraan in its Arabic to be the unaltered and final revelation of God. People of all ages and cultures respond to humour. Most people are able to experience humour be amused, smile or laugh at something funny and thus are considered to have a sense of humour.