Answer
Carol of the Bells is the English-language title of a Christmas song with music by Mykola Leontovych. It is the most famous composition of Leontovych, who was a Ukrainian composer, teacher, conductor, and ethnomusicologist. The song is based on a Ukrainian folk song called Shchedryk, which is sung during the Ukrainian holiday of Shchedryk-Vechir (also known as Little Christmas Eve).