Today carols are regularly sung at Christian religious services. Some compositions have words that are clearly not of a religious theme, but are often still referred to as "carols". For example, the 16th-century song "A Bone, God Wot!" appears to be a wassailing song (which is sung during drinking or while requesting ale), but is described in the British Library's Cottonian Collection as a Christmas carol. As recently as 1865, Christmas-related lyrics were adopted for the traditional English folk song Greensleeves, becoming the internationally popular Christmas carol "What Child is This?". Little research has been conducted on carol singing, but one of the few sociological studies of caroling in the early 21st century in Finland determined that the sources of songs are often misunderstood, and that it is simplistic to suggest caroling is mostly related to Christian beliefs, for it also reinforces preservation of diverse national customs and local family traditions.