A marriage license is permission from a legal authority (either church or state) for the marriage of two people to be performe. The details of how licenses are obtained, and in what circumstances, has differed between countries and throughout history. Licenses to marry began in the Middle Ages, when their purpose was to give permission for a marriage which would otherwise be illegal (for instance, if the necessary period of notice for the marriage had not been given). However, in some modern jurisdictions they have become a statutory requirement for a marriage to take place and may even serve as the record of the marriage itself. In others, valid marriages can occur without a license (for example, in places where licenses are not mandatory, in cases where a couple obtain a pardon for having married without license, or in jurisdictions permitting common law marriage, by cohabitation and representation as spouse and spouse).