What is a carol? Where does the word come from?

In old French a 'carole' was circle dance accompanied by singing.

Carols written and sung for all four  seasons. They were linked to the agricultural calendar, with harvest carols for example. 

Though predating Christianity, carols were adapted by the church.  Christmas carols originated from pagan mid-winter festivals but developed into the modern tradition 19th Century. 

Song Stories

When Dickens called his story A Christmas Carol he was referring to the tradition of story telling through song - with the five staves mimicking verses. 

Though there is a recognizably Christian theme of redemption, there are no specifically Biblical references. The ghosts, for example, are clearly secular.

Carol services 

Popular carols come from very disparate sources. The Coventry Carol, one of the oldest and darkest, is a 16th Century commemoration of the Slaughter of the Innocents. 

While Shepherds Watch Their Flocks from the same period is more suitable for the Nativity play market, but protestants cheerfully singing O Come All Ye Faithful may not realise that it is a call for a Catholic restoration.

Carol singing particularly popular in the Anglican church. This is formalised in the Service of Nine Lessons and Carols - most famously from Kings College, Cambridge. Biblical verses