The Requiem or Requiem Mass, also known as the Missa pro defunctis (Latin, “Mass for the deceased”) or Missa defunctorum (“Mass of the deceased”), is a liturgical service of the Roman Catholic Church celebrated by the priest presider for the repose of the soul of a particular deceased person or persons. It is frequently, but by no means always, celebrated in the context of a funeral.

Outside the Catholic Church, the ceremony is used in the Anglo-Catholic branch of Anglicanism and in certain Lutheran churches. A comparable service, with a wholly different ritual form and texts, exists in the Eastern Orthodox and Eastern Catholic Churches.

The term “Requiem” is the accusative form of the Latin noun requies (rest, repose). The introit of the liturgy begins with the words “Requiem aeternam dona eis, Domine” – “Grant them eternal rest, O Lord”.

The Requiem Mass is notable for the large number of musical compositions that it has inspired, including the requiems of Mozart, Verdi and Fauré. Originally, such compositions were meant to be performed in liturgical service, with monophonic chant. Eventually the dramatic character of the text began to appeal to composers to an extent that they made the requiem a genre of its own, and the requiems of composers such as Verdi are essentially concert pieces rather than liturgical works.

Celebrations of the Requiem Mass were often referred to as “black Masses”, from the colour of the vestments worn by the priest and the altar cloths. The term has no connection with the Satanist ritual of the same name. Since the liturgical reform of 1969–1970, the colour black has been replaced with purple in requiems celebrated in the ordinary form of the Roman Catholic liturgy…