A Papal Bull is an official decree or letter issued by the Pope, the leader of the Roman Catholic Church. The term "bull" comes from the Latin word "bulla," which refers to the lead seal used to authenticate the document. Papal Bulls can address various matters, including doctrine, canon law, and important church appointments. These documents have played a significant role in the history of the Church and its relationship with the world. Notable examples include the Papal Bull of 1493, which granted Spain and Portugal rights to colonize the New World, and the Papal Bull of excommunication, which can declare someone outside the Church's grace.