"Ecclesiastical heraldry refers to the use of heraldry within the Christian Church for dioceses and Christian clergy. Initially used to mark documents, ecclesiastical heraldry evolved as a system for identifying people and dioceses. It is most formalized within the Catholic Church, where most bishops, including the Pope, have a personal coat of arms. Clergy in Anglican, Lutheran, Eastern Catholic and Eastern Orthodox churches follow similar customs, as do institutions such as schools and dioceses.
Ecclesiastical heraldry differs notably from other heraldry in the use of special insignia around the shield to indicate rank in a church or denomination. The most prominent of these insignia is the low crowned, wide brimmed ecclesiastical hat, commonly the Roman galero. The color and ornamentation of this hat indicate rank. Cardinals are famous for the "red hat", while other offices and churches have distinctive colors of hat, such as black for priests and green for bishops, customarily with a defined number of tassels that increases with rank." - (en.wikipedia.org 15.02.2022)
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