Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A courtesy title is a form of address in systems of nobility used by children, former wives and other close relatives of a peer. These styles are used ''by courtesy'' in the sense that the users do not themselves hold substantive titles. There are several different kinds of courtesy titles in the British peerage.If a peer of one of the top three ranks (a duke, marquess or earl) has more than one title, his eldest son, not himself an actual peer, may use one of his father''s lesser titles ''by courtesy''. However, the father continues to be the substantive holder of the peerage title and the son using the peerage by courtesy legally remains a commoner. If the eldest son of a duke or marquess has an eldest son, he may use a still lower title if one exists.