Choir
​Anglican church music is written for choir with or without organ accompaniment. Adult singers in a cathedral choir are often referred to as lay clerks, while children may be referred to as choristers or trebles. In certain places of worship, such as Winchester College in England, the more archaic spelling quirister is used. An Anglican choir typically uses "SATB" voices (soprano or treble, alto or counter-tenor, tenor, and bass), though in many works some or all of these voices are divided into two for part or all of the piece; in this case the two halves of the choir (one on each side of the aisle) are traditionally named decani and cantoris which sing, respectively, Choir 1 and Choir 2 in two-choir music. There may also be soloists, usually only for part of the piece. There are also works for fewer voices, such as those written for solely men's voices or boys'/women's voices. At traditional Anglican choral services, a choir is vested, i.e. clothed in special ceremonial vestments. These are normally a cassock, a long, full-length robe which may be purple, red or black in colour, over which is worn a surplice, a knee-length white cotton robe. Normally a surplice is only worn during a service of worship, so a choir often rehearses wearing cassocks only. Younger choristers who have newly joined a choir begin to wear a surplice after an initial probationary period. Cassocks originated in the medieval period as day dress for clergy, but later came into liturgical use. Additionally, junior choristers may wear a ruff, an archaic form of dress collar, although this tradition is becoming less common. In some establishments, including the Choir of King's College, Cambridge, Eton collars are worn.