High Quality Content by WIKIPEDIA articles! A Papal bull is a particular type of letters patent or charter issued by a pope. It is named after the bulla that was appended to the end in order to authenticate it. Papal bulls were originally issued by the pope for many kinds of communication of a public nature, but after the fifteenth century, only for the most formal or solemn of occasions. Modern scholars have retroactively used the term "Bull" to describe any elaborate papal document issued in the form of a decree or privilege (solemn or simple), and to some less elaborate ones issued in the form of a letter. Popularly, the name is used for any papal document that contains a metal seal.