This garment is a religious garment worn by the Catholic Church.
Choir dress is the traditional vesture of the clerics, seminarians and religious of Christian churches worn for public prayer and the administration of the sacraments except when celebrating or concelebrating the Eucharist.
Choir dress in the Catholic Church is worn by deacons, priests, regular prelates, bishops and cardinals when presiding at or celebrating a liturgy that is not the Mass, especially the Liturgy of the Hours. Before the Second Vatican Council the dress was more elaborate, and had dozens of varieties and colors. After The Second Vatican Council, it was reduced, however exceptions are sometimes granted for cathedral chapters. The current dress is worn when attending Mass without celebrating or observing the Eucharist. It is worn by seminarians, instituted lectors and acolytes, and altar servers and choir members at Mass or other liturgical events.
The choir dress differs from the vestments worn by the celebrants of the Eucharist, being normally made of fabrics such as wool, cotton or silk, as opposed to the fine brocades used in vestments. It may also be worn by lay assistants such as acolytes and choirs.
The choir dress differs from "house dress" which is worn outside of a liturgical context (whether in the house or on the street). House dress may be either formal or informal.
Like Eucharistic vestments it derived originally from the formal secular dress of the Roman Empire in the first centuries of the Christian era which survived in church usage after fashion had changed.