Baron is a specific title of nobility or a more generic feudal qualification. The word baron comes from French baron, itself from Frankish baro meaning "freeman, warrior"; it merged with cognate Old English beorn meaning "nobleman." Ultimately it seems to mean a burden bearer.

In the British peerage system, barons rank lowest, coming after viscounts. A female of baronial rank has the honorific baroness. A baron may hold a barony (plural baronies).

William the Conqueror introduced "baron" as a rank into England to distinguish the men who had pledged their loyalty to him (see Feudalism). Previously, in the Anglo-Saxon kingdom of England, the king's companions held the title of earls and in Scotland, the title of thane. All who held their barony "in chief of the king" (i.e. directly from William and his successors) became alike barones regis (barons of the king), bound to perform a stipulated service, and welcome to attend his council. Before long, the greatest of the nobles, especially in the marches, such as the Earls of Chester or the Bishops of Durham, might refer to their own tenants as "barons", where lesser magnates spoke simply of their "men" (homines).

Initially those who held land direct of the crown by military service, from earls downwards, all alike bore the title of baron, but under Henry II, the Dialogus de Scaccario already distinguishes greater or lesser baronies. Within a century of the Norman Conquest, as in Thomas Becket's case (1164), there arose the practice of sending to each greater baron a special summons to the council that evolved into the House of Lords, while the lesser barons, Magna Carta (1215) stipulated, would receive summons only in general, through the sheriffs. Thus appeared a definite distinction, which eventually had the effect of restricting to the greater barons the rights and privileges of peerage.

The King of England could create a new barony in one of two ways: by a writ of summons directing someone to Parliament, or by letters patent. Writs of summons featured in medieval times, but creation by letters patent has become the norm. Baronies thus no longer directly relate to land ownership.

In Scotland, the rank of baron refers to the holder of a feudal barony, which does relate to the feudal jurisdiction over the territorial entity. Scottish (feudal) barony is a dignity of honour ranked as titled nobility, as HM Lyon Court ruled 26th February 1943 and thereafter confirmed by the Court of Session. Curiously, but in the UK this normal continental style (titled nobility) in almost meaningless (confused with Peerage of the Realm), and in use in Scotland only where the nobiliary Law system is very different from English one. Therefore the rank of Scottish baron is in absolutely similarity with the Freiherr in the Holy Roman Empire, and fell into the category Uradel (old feudal nobility). By the Feudal Law, a Scottish barony erected by the Crown makes its holders full equivalent of Reichsfreiherr (in old German sense). If such a barony was granted together with a "coronatoris regalitatis" (regality – the semi-sovereign power of justice) the holder of such a barony is equivalent of Hochadel ( high semi-sovereign noble in old German sense). All Scottish baronies were erected with remainder "to heirs and assignees of feudal right over the territorial entity". But with the end of feudalism in Scotland, after 28 November 2004 the dignity of a Scottish Baron became a purely hereditary title of honour, ranking (curiously) below all baronets(!) and above all Clan Chiefs (who are not peers of the Realm). This table of precedence is based on Baronetcy Warrant by King Charles I, and is contradicts to a number of constitutional norm of legislation which confirms for all (feudal) baronies of Scotland pre-dated 1707 status amongst the Peerage of Scotland.The Scots system does not have baronies as in England, but "Lordships of Parliament".But, at least one of Scottish feudal barony was recognised by the Crown and House of Lords as a Lordship in the Peerage of Scotland, without any Writ of Summons or Letters Patent granting peerage. It is Barony of Torphichen, granted on 24 January1564 by Crown Charter for James Sandilands, his heirs and assignees of feudal right over territorial entity. Generally, the more modern baronies pass only to male heirs. However, in the cases of Scottish Lordships of Parliament and of English baronies by writ a daughter can inherit provided she has no brothers. In the English case, if there are multiple daughters, they jointly inherit the barony as coheirs, which then falls into abeyance until there is only one heir again. The Scottish equivalent of the English baron is Lord of Parliament.

In the late twentieth century Britain introduced the concept of non-hereditary life peers. All appointees to this distinction have taken place at the rank of baron, though in principle nothing prevents the creation of a life peerage of higher rank. Baronies are often subsidiary titles, thus being used as courtesy titles by eldest sons.

Non-Scottish barons are styled The Right Honourable The Lord [Barony]. Baron's wives are titled The Right Honourable The Lady [Barony]. Baronesses in their own right are either titled The Right Honourable The Baroness [Barony] or The Right Honourable The Lady [Barony], mainly based on personal preference (for an example of the former, see Margaret Thatcher). Right Honourable is frequently abbreviated to Rt. Hon. When referred to by the Sovereign in public instruments, The Right Honourable is changed to Our right trusty and well-beloved cousin (even if the said baron is not their blood cousin), with and counsellor attached if they are a Privy Counsellor.

Courtesy barons are styled simply Lord [Barony], and their wives are Lady [Barony]. The style of Right Honourable is not used for them.

Normally one refers to or addresses Baron X as Lord X and his wife as Lady X. In the case of women who hold baronies in their own right, they can be referred to as Baroness X as well as Lady X. In direct address, they can also be referred to as My Lord or My Lady. The husband of a Baroness in her own right does not receive a style. Children of Barons and Baronesses in their own right, whether hereditary or for life, have the style The Honourable [Forename] [Surname]. After the death of the father or mother, the child may continue to use the style Honourable.

In Germany all the knightly families (distinguished by the prefix "von") eventually were recognised as of baronial rank. Families which had always held this status were called Uradel or Original Nobility, and were heraldically entitled to a seven pointed coronet. Families which had been ennobled at a definite point in time had only five points on their coronet. These families held their titles from their lord. The holder of an allodial (ie free-standing) barony was thus called a Free Lord, Freiherr and its various variations occupy the same rank as a foreign Baron, exclusively (as in the Holy Roman Empire) or concurrently.

The non-allodial barony, whether original or created, is of small value because it descends to all sons and daughters of the male line. The holders of original titles distinguish themselves from the newcomers by abbreviating "von" as "v."

The title was quite common in most European countries, in various languages (whether Germanic, Romance, Slavonic or other), often in a slightly modified form. The following list includes the male and female forms and (sometimes) the territorial domain. Notice, especially for the 'alternative' Freiherr-type titles, that the existence of a word does not always implies the actual use : it is a mere rendering of foreign realities.

In some republics of continental Europe, the title of "Baron" retains a purely social prestige, with no particular political privileges. In the Polynesian island monarchy of Tonga, as opposed to the situation in Europe, barons are granted this imported title (in English), and continue to hold and exercise some political power.

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. {{cite encyclopedia}}: Missing or empty |title= (help)