A baron is a member of the nobility, with a rank which varies depending on the nation. In England and Japan, for example, barons are at the bottom rung of the nobility. Many countries use the title of baron or some variation thereof in the ranking systems for their noble classes, and the title may be conferred or inherited. The female version of a baron is a baroness.

The word is derived from the Spanish barón, which was in turn taken from the Frankish word baro, which refers to a nobleman or warrior. In most European countries, barons played an important role in feudal society by managing land and tenants and defending the king, if necessary. In England, a baron actually swore loyalty specifically to the king or another high ranking noble. In return for this loyalty, the baron was granted a gift of land and serfs, which could be used to make a living.

A land grant given to a baron is known as a barony. Some baronies were historically quite large, and many have passed out of the control of barons in the modern era, since the role of the nobility in general society has changed. Barons, for example, no longer control the lives of serfs and servants, and they may not always be members of the military responsible for defending their monarchs and home nations.

Barons are entitled to wear certain ceremonial items, including coronets and robes trimmed with ermine. The specifics of these items, such as the number of rows of ermine and number of jewels in a coronet vary, depending on the nation, and these items are only worn at ceremonial occasions. Since the subtleties of the nobility are quite complex, barons may consult a professional to make sure that they dress and behave appropriately. Barons are also entitled to formal address; again, this varies from nation to nation, with many barons known as “The Right Honorable” or “Lord,” and baronesses are also entitled to these courtesies.

In the modern era, someone becomes a baron in one of three ways. The child of a baron will inherit the title, although some members of the nobility have chosen to reject their titles in the interest of social equality. A baron can also be created through letters patent, formal papers from a monarch which are issued to create a new formal office or right. In England, a baron can also be created through a writ of summons which orders someone to Parliament, effectively creating a new barony. Hereditary peers used to form an important part of the Parliament, sitting in the House of Lords; as of 1999, only 92 hereditary peers sit on the House of Lords.