Lords are anyone who owns a castle and rules over at least 100 square miles of land. Out in the Wilderness they are beholden to no one and receive the full fruit of their lands. In the Realm, they must receive their land from a Duke or Prince and pay him 25% of his tax revenue. If a lordship in The Realm lasts for 3 generations of one family, the lord can petition for promotion to Baron. Barons only pay 15% of their income to the Duke or Prince, they also have honor precedence over lords.
In addition to paying tax revenue to their overlords, the lords and barons are expected to provide troops for 2 months’ service per year. At a minimum, they must provide 5 knights, their squires and mounts, and 15 foot soldiers or lighter cavalry, but the exact military obligation varies and is established when the fee first granted.