Canopy, in general, is an ornamental covering of cloth, stone, wood, or metal, used to crown an altar, throne, pulpit, statue, etc. In liturgical language, the term is commonly employed to designate (a) the structure covering an altar, formerly fitted with curtains and supported on four pillars; (b) the covering suspended over the throne occupied by dignitaries of the Church or princes; (c) the covering under which the Blessed Sacrament is sometimes borne in processions etc. In medieval times altars were protected by a covering then called a ciborium (see the article Altar. under subtitle Ciborium), but now known as a baldachinum (q.v.), or canopy, which survives at the present day as a feature of certain styles of architecture. When an altar had no ciborium it was covered with a cloth called a dais. As a mark of distinction bishops and higher prelates have a right to a covering over the thrones which they occupy at certain ecclesiastical functions. This is called a canopy. It is sometimes granted by special privilege to prelates inferior to bishops, but always with limitations as to the days on which it may be used and the character of its ornamentation. When bishops assist at solemn functions in the churches of regulars the latter are bound to provide the episcopal seat with a canopy (Cong. Bishops and Regulars, 1603). Princes enjoy similar privileges, but their seats should be outside the sanctuary, and regulated in accordance with custom. The color of the canopy should correspond with that of the other vestments. Two kinds of canopy are employed in processions of the Blessed Sacrament. One of small dimensions and shaped like an umbrella—except that it is flat and not conical—is called an ombrellino. It is provided with a long staff by which it is held. The other, called a baldacchino, is of more elaborate structure and consists, in main outline, of a rectangular frame-work of rich cloth, supported by four, six, or eight staves by which it is carried. In both cases the covering consists of cloth of gold, or silk of white color. The ombrellino is used for carrying the Blessed Sacrament to the sick and for conveying it from the altar to the baldacchino. The latter is used for all public processions, when it is borne by nobles of the highest rank, the more worthy holding the foremost staves. It is forbidden to carry relics of the saints under the baldacchino, but this honor may be given to those of the Sacred Passion (Cong. of Rites, May, 1826).