The custom of singing carols during the Christmas season goes back to the time when people sang in churches as part of the nativity plays. Between then and the 13th century St.Francis of Assisi  transformed the songs into everyday language so that common people could understand them. He also promoted their use at popular festivals, and his travelling ministrels (later known as 'waits') provided Yutelide music. Some famous carols are:

 

The Twelve Days of Christmas

Silent Night

Away in a Manger

Jingle Bells

Rudolf the Red Nose Reindeer