Baron is a title of honor in many European peerage systems. It is often a hereditary title that ranks as the one of the lower titles in a peerage. In the UK peerage system, the five peerage titles from highest to lowest are duke, marquess, earl, viscount and baron. Baronets and knights are not members of the peerage although a baron may also be a knight. In medieval England a baron was a tenant-in-chief who held his lands directly from the king. During the 13th century barons were summoned by royal writ to attend Parliament.
The word baron comes from Old French baron, itself from Frankish baro meaning "freeman, warrior". It later merged with Old English beorn meaning "nobleman." The lands of a baron are called a barony. The female title for a baron is baroness. The form of address for a baron is "Lord" and for a baroness "Lady".