Knight is the English term for a European social position. Knighthood is a non-heritable (with a few rare exceptions) form of gentility, but not of nobility. In the High and Late Middle Ages, the principal duty of a knight was to fight as, and lead, heavy cavalry (see also serjeanty); more recently, knighthood has been a title of honor, given to a more diverse class of people, from Sir Edmund Hillary to Sir Paul McCartney. By extension, "knight" is also used as a translation of the names of other honorable estates connected with horsemanship, especially from classical antiquity.

The history of knighthood involves, therefore, the history of the social institution, which began somewhat differently in the various European regions; the history of the word, and the corresponding terms in French and Latin; and the history of the technology which made heavy cavalry possible.

The word knight derives from Old English cniht, meaning page boy, or servant (as is still the case in the cognate Dutch and German Knecht for servant), or simply boy. Knighthood, as Old English cnihthad, had the meaning of adolescence, i.e. the period between childhood and manhood. The sense of (adult) lieutenant of a king or other superior was in existence at least as early as 1100, although there are signs of it as early as Alfred's Orosius.

In this respect English differs from most other European languages, where the equivalent word emphasizes the status and prosperity of war horse ownership. In German, the literal meaning of Ritter is rider; in Dutch, the literal meaning of Ridder is Ruiter.

Interestingly, in the later Roman Empire the classical Latin equus for horse was replaced in common parlance by vulgar Latin caballus, derived from Gaulish caballos (Delamare 2003 p.96), thus giving French cheval (keval), Italian cavallo, and (borrowed from French) English cavalry. This formed the basis for the word knight among the romance European languages: Spanish caballero, French chevalier, Portuguese cavaleiro etc.

Linguistically, the association of horse ownership with social status extends at least as far as ancient Greece, where many aristocratic names incorporated the Greek word for horse, like Hipparchus and Xanthippe; the character Pheidippides in Aristophanes' Clouds has his grandfather's name with hipp- inserted to sound more aristocratic. A survival is the modern given name Philip, whose etymology means lover of horses.

In the early Middle Ages the rank of knight was loosely defined. In late Carolingian France (10th Century) persons occupying this role were termed miles (plur. milites). This term designated a professional fighting man in the emerging feudal system. Many were as poor as the peasant class. However, over time, as this class of fighter became more prominent in post-Carolingian France, they became wealthier and began to hold and inherit land. Eventually fighting on horseback became synonymous with the warrior caste's role.

From the 12th century, the concept continued being tied to cavalry, mounted and armoured soldiers, and thus to the earlier class of noble Roman warriors known as equites (see esquire). Because of the cost of equipping oneself in the cavalry, the term became associated with wealth and social status, and eventually knighthood became a formal title. Significantly the nobility, who at this time were also expected to be leaders in times of war, responded to this new class by becoming members of it. Nobles had their sons trained as gentlemen and as professional fighters in the household of another noble. When the young man had completed his training he was ready to become a knight, and would be honoured as such in a ceremony known as "dubbing" (knighting) from the French "adoubement". It was expected that all young men of noble birth be knights and often take oaths swearing allegiance, chastity, protection of other Christians, and respect of the laws laid down by their forebears, though this varied from period to period and on the rank of the individual.

Ranks: From the time of Henry III of England, a knight bachelor was a member of the lower nobility, preceded by the knight banneret, a commander of ten or more lances who could lead his men under his own banner, but who did not have the rank of baron or earl. The knights bachelor did not wear any insignia until 1296.

The concept, together with the notion of chivalry came to full bloom during the Hundred Years' War. During the same period, however, the importance of heavy cavalry was reduced by improved pikemen and longbow tactics. This was a bitter lesson for the nobility, learned throughout the 14th century at battles like those of Crécy, Bannockburn and Laupen. The "knights in shining armour" of the late 15th and 16th centuries, by that time in full plate armour, were mostly confined to the jousting grounds, and the romantic Pas d'Armes. The chess piece was named in this period, around 1440. Via the transitional Cuirassiers of the 16th century, cavalry again became dominant in light, unarmoured form, in the 17th century, and not usually associated with knighthood.

Knighthood as a purely formal title bestowed by the British monarch unrelated to military service was established in the 16th century. The British title of baronet was established by James I of England in 1611 as an inheritable knighthood, ranking below Baron (the lowest Peerage title).

An Equestrian (Latin eques, plural equites) was a member of the second highest social class in the Roman Republic and early Roman Empire. This class is often translated as knight; the medieval knight, however, was called miles in Latin, (which in classical Latin meant "soldier", normally infantry), until the Renaissance revival of eques.

Similarly, the Greek ιππευς (hippeus) is commonly translated knight; at least in its sense of the highest of the four Athenian social classes, the ones who could afford to maintain a warhorse in the state service.

During the High Middle Ages, it was technically possible for every free man to become a knight, but the process of becoming (and the equipping of) a knight was very expensive; thus it was more likely that a knight would come from a noble (or wealthy) family. They went through a long process to become a knight involving three stages: after starting as a page, they moved on to being a personal squire, and after they had passed their training they could be knighted.

The process of training for knighthood began before adolescence, inside the prospective knight’s own home, where he was taught courtesy and appropriate manners. Around the age of 7 years, he would be sent away to train and serve at a grander household as a page. Here, he would serve as a kind of waiter and personal servant, entertaining and serving food to his elders. A page was usually the son of a vassal, who sent him to his or another lord’s castle to become a page. For seven years a page was cared for by the women of the house, who instructed him in comportment, courtesy, cleanliness, and religion. He would learn basic hunting and falconry, and also various battle skills such as taking care of, preparing, and riding horses, as well as use of weapons and armour.

A page became a squire when he turned 14 years of age, being assigned or picked by a knight to become his personal aide. This allowed the squire to observe his master while he was in battle, in order to learn from his techniques. He also acted as a personal servant to the knight, taking care of his master’s equipment and horse. This was to uphold the knight’s code that promoted generosity, courtesy, compassion, and most importantly, loyalty. The knight acted as a tutor and taught the squire all he needed to know to become a knight. As the squire grew older, he was expected to follow his master into battle, and attend to his master if the knight fell in battle. Some squires became knights for performing an outstanding deed on the battlefield, but most were knighted by their lord when their training was judged to be complete.

A squire could hope to become a knight when he was about 18 to 21 years old. Once the squire had established sufficient mastery of the required skills, he was dubbed a knight. In the early period, the procedure began with the squire praying into the night, known as vigil. He was then bathed, and in the morning he was dressed in a white shirt, gold tunic, purple cloak, and was knighted by his king or lord. As the Middle Ages progressed, the process changed. The squire was made to vow that he would obey the regulations of chivalry, and never flee from battle. A squire could also be knighted on the battlefield, in which a lord simply performed the accolade, i.e. struck him on the shoulder saying “Be thou a knight”.

The night before his knighting ceremony, the squire would take a cleansing bath, fast, make confession, and pray to God all night in the chapel, readying himself for his life as a knight. Then he would go through the knighting ceremony the following day. Knights followed the code of chivalry, which promoted honor, honesty, respect to God, and other knightly virtues. Knights served their lords and were paid in land, because money was scarce.

Later, as military technology and society evolved, knighthood became irrelevant to warfare (the Battle of the Golden Spurs in 1302 was seen as a landmark: the largest knightly army in Christendom, fielded by the French king, was destroyed by infantry; soon firearms would revolutionize war still further), while its theoretically irrelevant link with nobility (generally only nobles were knighted, and in noble families most males were expected to be) encouraged it to survive with an essentially civilian ethos of social stratification. In various traditions, knighthood was reserved for people with a minimum of noble quarters (as in many orders of chivalry), or knighthood became essentially a low degree of nobility, sometimes even conferred as a hereditary title below the peerage. Meanwhile monarchy strived, as an expression of Absolutism, to monopolize the right to confer knighthood, even as an individual honour. Not only was this often successful, once established, this prerogative of the Head of State was even transferred to the successors of dynasties in republican regimes, such as the British Lord Protector of the Commonwealth.

Knighthood was closely connected with the feudal system. Originating largely in what later became known as France, this was a social organization in which warfare and the protection of the common people became the specialized skill of a select group. Since, at the time, even the monarch was short of cash, they were paid in land. These rather extensive pieces of land were the fiefs. Though a fief did not have to be land — it could be any payment — it is generally thought of as being the land that the knights were given as payment for service to the king. The knights were economically supported by peasants who worked to produce food and ideologically supported by the contemporary church.

In times of war or national disorder the monarch would typically call all the knights together to do their annual service of fighting. This could be against threats to the nation or in defensive and offensive wars against other nations. Sometimes the knights responding to the call were the nobles themselves, and sometimes these men were hired by nobles to fight in their stead; some noblemen were disinclined or unable to fight.

As time went by, monarchs began to prefer standing (permanent) armies because they could be used for longer periods of time, were more professional and were generally more loyal; partly because those noblemen who were themselves knights, or who sent knights to fight, were prone to use the monarch's dependency on their resources to manipulate him. This move from knights to standing armies had two important outcomes: the implementation of a regular payment of "scutage" to monarchs by noblemen (a money payment instead of active military service) which would strengthen the concept and practice of taxation; and a general decrease in military discipline in knights, who became more interested in their country estates and chivalric pursuits, including their roles as courtiers.

Originally, knighthood could be bestowed on any man by a knight commander, but it was generally considered more prestigious to be dubbed a knight by the hand of a monarch or royalty; most monarchs eventually acquired the exclusive right to confer knighthoods known as Fount of honour. By about the late 13th century, partly in conjunction with the focus on courtly behavior, a code of conduct and uniformity of dress for knights began to evolve. Knights were eligible to wear a white belt and golden spurs as signs of their status. Moreover, knights were also required to swear allegiance to a superior in the feudal pyramid — either to a liege lord or to a military order.

In theory, knights were the warrior class defending the people of feudal Christianity and bound by a code of chivalry. Chivalry, like the samurai’s bushido, was a set of customs that governed the knights' behavior, but was perhaps less scrupulously observed. Knights served mightier lords, usually as vassals, or were hired by them. Some had their own castles, while others joined a military order or a crusade. In reality, rules were often bent or blatantly broken by knights as well as their masters, for power, goods or honor. So-called robber knights even turned to organized crime, some based in a castle.

In some countries, knighthood was merged into the nobility, remaining only as a low or genetic noble title; thus the aristocratic estate's chambers in the diets of the realms of Sweden and Finland were each called House of knights.

There are three hereditary knighthoods in Ireland, the third of which is extinct, namely

• Knight of Glin, the Black Knight, (Fitzgerald of Limerick)
• Knight of Kerry, the Green Knight, (Fitzgerald of Kerry)
• The White Knight, (FitzGibbon)

Baronetcies are hereditary but are not knighthoods.

In war, the chivalrous knight was idealized as brave in battle, loyal to his king and God, and willing to sacrifice himself for the greater good. Towards his fellow Christians and countrymen, the knight was to be merciful, humble, and courteous. Towards noble ladies above all, the knight was to be gracious and gentle.

• Knights Hospitaller, founded during the First Crusade, 1099 to present.
• Order of Saint Lazarus established ca. 1100, abolished 1830.
• Knights Templar, founded 1118, disbanded 1307.
• Teutonic knights, founded ca. 1190, ruling Prussia until 1525.

Other orders were established in the Iberian peninsula in imitation of the orders in the Holy Land, in Avis in 1143, in Alcantara in 1156, in Calatrava in 1158, in Santiago in 1164.

After the failure of the Crusades, the military orders became idealized and romanticized, resulting in the late medieval notion of chivalry, as reflected in the Arthurian romances of the time. The creation of chivalric orders was fashionable among the noblesse in the 14th and 15th centuries, as remains reflected in contemporary honours systems, and the term order itself, notably the Order of Saint George, founded by Charles I of Hungary in 1325/6, the Order of the Garter, founded by Edward III of England in ca. 1348, the Order of the Golden Fleece, founded by Philip III, Duke of Burgundy in 1430, and the Order of St Michel, founded by Louis XI of France in 1469.

From roughly 1560, purely honorific orders were established, designed as a way to confer prestige and distinction, unrelated to military service or chivalry in the more narrow sense. Such orders were particularly popular in the 17th and 18th centuries, and knighthood continues to be conferred in various countries:

• The United Kingdom (see British honours system) and some Commonwealth of Nations countries;
• Most European countries, such as The Netherlands (see below).
• Malaysia — see Malay titles;
• Thailand;
• The Holy See — see external link [1] Papal Orders.

There are other monarchies and also republics that also follow the practice. Modern knighthoods are typically awarded in recognition for services rendered to society, services which are no longer necessarily martial in nature. The musician Elton John, for example, is entitled to be called Sir Elton. The female equivalent is a Dame.

Accompanying the title is the given name, and optionally the surname. So, Elton John may be called Sir Elton or Sir Elton John, but never Sir John. Similarly, actress Judi Dench D.B.E. may be addressed as Dame Judi or Dame Judi Dench, but never Dame Dench. Wives of knights, however, are entitled to the honorific "Lady" before their husband's surname. Thus Sir Paul McCartney's wife is styled Lady McCartney, not Lady Paul McCartney or Lady Heather McCartney. The style Dame Heather McCartney could be used; however, this style is largely archaic and is only used in the most formal of documents.

State Knighthoods in the Netherlands are issued in three orders, the Order of William, the Order of the Dutch Lion, and the Order of Orange Nassau. Additionally there remain a few hereditary knights in The Netherlands.

In Italy, the Cavalieri is an honor equivalent to a knighthood.

In France, there is the Ordre des Arts et des Lettres. The lowest of the three ranks conferred by this academy is knighthood.

• Boulton, D'Arcy Jonathan Dacre. The Knights of the Crown: The Monarchical Orders of Knighthood in Later Medieval Europe, 1325-1520. 2d revised ed. Woodbridge, Suffolk: Boydell Press, 2000.
• Forey, Alan John. The Military Orders: From the Twelfth to the Early Fourteenth Centuries. Basingstoke: Macmillan Education, 1992.
• Shaw, William A. The Knights of England: A Complete Record from the Earliest Time 2v. London: Central Chancery, 1906 (Baltimore: Genealogical Publishing Co., 1970).

• vityaz and bogatyr, Kievan Rus' terms translated as "knight".
• Samurai a similar class in Japanese history
• Xiá, a similar class in Chinese history
• Knight-errant
• Jedi Knight
• cavalry tactics

• "History of Orders of Chivalry". Heraldica. Retrieved June 18. {{cite web}}: Check date values in: |accessdate= (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
• Bartleby.com
• "Papal Orders of Chivalry".