Kol Nidre is the Aramaic prayer that opens the evening service on Yom Kippur, the holiest day in the Jewish calendar, when worshippers seek atonement and begin a day of fasting and reflection. Its haunting melody is one of the most recognisable pieces of Jewish liturgical music and has been performed for generations by cantors, choirs and solo instruments, often on cello. Online, short instrumental versions circulate as transition music, because the tune is instantly associated with solemnity, memory and a pause for thought, even for listeners who do not know its words.