The banns of marriage, commonly known simply as the "banns" or "bans" (from a Middle English word meaning "proclamation", rooted in Frankish and thence in Old French), are the public announcement in a Christian parish church, or in the town council, of an impending marriage between two specified persons. It is commonly associated with the Catholic Church, the Church of Sweden (Lutheran), the Church of England (Anglican), and with other Christian denominations whose traditions are similar. In 1983, the Catholic Church removed the requirement for banns and left it to individual national bishops' conferences to decide whether to continue the practice, but in most Catholic countries the banns are still published.

The purpose of banns is to enable anyone to raise any canonical or civil legal impediments to the marriage, so as to prevent marriages that are invalid. Impediments vary between legal jurisdictions, but would normally include a pre-existing marriage that has been neither dissolved nor annulled, a vow of celibacy, lack of consent, or the couple's being related within the prohibited degrees of kinship.