What is a Papal Bull?

Papal Bull is the term used for a special kind of letters patent or charter issued by a Pope and named for the seal. A bulla is a seal. Papal Bull was named after the bulla that was appended to the end in order to authenticate it. They have been used by Pope for various kinds of communications since 6th century but after 15th century they are mostly used in formal and solemn of occasions. It is issued by Vatican Chancery in the name of the Pope.