The Seven Kingdoms is a feudal society. Below the King and the royal family rank the Great Houses (House Arryn, House Baratheon of Storm's End, House Greyjoy, House Martell, House Stark, House Targaryen, House Tully, and House Tyrell), followed by other noble houses, both greater and small, knights (landed knights, household knights, and hedge knights), and commoners. Nobles are addressed as "my lord" by other highborns, or "m’lord" by the smallfolk. Commoners might be addressed as goodwoman or goodman.
Every noble house has a house motto, while a coat of arms can be used by both nobility and knights, as a sign of status and identification (e.g. on the battlefield). Both nobles and knights can be ransomed, so in battle it might be preferred to capture them instead of killing them. Three hundred golden dragons is considered to be a fair ransom for a knight, whereas a nobleman’s son might be ransomed for three thousand golden dragons] A noble prisoner can be treated with honor and be kept in isolation in rooms as his status requires. However, making offense can result in the loss of the right for such honorable treatment.
At feasts, great honor can be given to a guest by seating him or her on the dais, with the place of highest honor being on the right side of the host. Being seated at the far end of the hall, far from the dais, however, is regarded as a place of little honor and regard] When a lord presides over a feast, he receives first choice of all dishes. He might send some of the especially fine dishes down to specific guests, showing friendship and respect.
Feudalism describes the society structure of the Seven Kingdoms, as it is largely resembles the feudal system of medieval Europe.
Feudalism was introduced to Westeros by the Andal tradition and is practised within the borders of the Seven Kingdoms. This society is based on a rigid social structure and government consisted of kings, lords, and the peasants. Nobles rule over the smallfolk within their territory through a system of fealty and sworn oaths. In this system each man owes military service to his lord in return for protection, a grant of land, and the peasants to work it.
The feudal system has a rigid structure of social classes. One cannot gain or lose the status; the impoverished, exiled, and powerless Daenerys Targaryen is still highborn, as is Alliser Thorne despite joining the Night's Watch to avoid execution, while former smuggler Davos Seaworth of Flea Bottom says that highborn do not consider him one of them despite his knighthood, land, keep, and banner.
Highborn status is desirable; bastard Jon Snow dreams that his unknown mother is "beautiful, and highborn". People expect highborn to differ from others in behavior, dress, speech, given names, and even their flowering and maidenheads. Highborn bastards have special surnames, highborn lords rarely ride with hedge knights (and highborn women are unlikely to marry them), and highborn prisoners of war are held for ransom when others are killed.
Those who are not highborn are lowborn or smallfolk. Smallfolk who become members of nobility are still lowborn, such as Janos Slynt's family despite his receiving Harrenhal and small council membership. Despite House Seaworth's creation most highborn scorn Ser Davos, and being lowborn embarrasses his sons, but if Stannis Baratheon wins the War of the Five Kings they may become knights, and Davos's grandchildren will be highborn. Most lowborn can, however, expect to die as commoners. There are no provisions for the advancement of individuals from a lower class into the higher classes. This is not to say that it is impossible, only that it is very difficult, usually bestowed by lords to those who have done a great service to them, or knights bestow the rank and title of Knighthood on any individual who has proven himself worthy.
The King on the Iron Throne, the Lord of the Seven Kingdoms, has the highest feudal rank; beneath him are the various lords and knights, with peasants, also known as smallfolk, at the bottom. The king sits on the Iron Throne, claims ownership of the land, has the final political authority and holds the ultimate power in all matters. Although in practice the king is constrained by political realities, and while no individual command is likely to be countermanded, he could still lose his position to intrigue if he were to offend the wrong people. Of course, as kings do not retire, this loss of position would involve his death.
Lord
In Westeros's system of nobility, above knights and below the king there are only lords, some greater and some lesser, some sworn to others, but all with the same title; the exception is the Lord of Sunspear, who still holds the title "Prince of Dorne". Nobility is hereditary, expressed through vassalage which connect between them the various owners of strongholds. Each lord has vassals; sometimes vassals have vassals.
The lords of the great houses have the highest ranks in their regions of the seven kingdoms, and are vassals only to the king. Petty lords at the bottom have a few villages. It is the Lord's responsibility to govern his lands, keep the king's peace, enforce law and justice on local matters, and ensure that taxes due to the king are collected in a timely manner.
Some lords have titles which belong only to their houses: House Greyjoy, for example, has the title of "Lord Reaper of Pyke", House Lannister has "Shield of Lannisport", House Royce of the Gates of the Moon has the title of Keeper of the Gates of the Moon made hereditary for them, and House Manderly has several titles, many of which relate to their past life in the Reach and make no sense in the North, but are preserved as tradition. These titles do not elevate a lord above others—the Prince of Dorne has no more authority than other great lords—but demonstrate a house's history.
There appear to be roughly one thousand or so families holding any lordly rank in the Seven Kingdoms. There are nine major regions in the Seven Kingdoms (including the riverlands and the crownlands), each of which has about a dozen or so major vassal houses (House Umber, House Glover, etc.). Each of these major lords in turn have anywhere from two or three to about a dozen minor lords who serve as their own vassals (House Cassel, House Forrester, etc.): 9 x 12 = 108, and 108 x 10 = ~1080 (plus the nine Great Houses themselves). This seems to loosely match the only explicit number of lords ever given, for the Great Council of Harrenhal in 101 AC: when it was said that almost all lords in the realm came to the council, and their number was given as roughly one thousand. The number of lordly houses is in flux, however, as over time some die out through war, or new ones are created by younger sons. Minor vassal houses, of course, have a higher turnover rate than major vassal houses.
A steward is a man responsible for running the day-to-day affairs of the castle and acting on the lord's behalf. He may be entrusted with the castle in the lord's absence.
Foreign societies also have hierarchies. A daughter of the Prince of Pentos, a sister of the Archon of Tyrosh, and highborn girls from Myr attended the Maiden's Day Cattle Show restricted to members of nobility.
Landed knights
Landed knights are the lowest rank of the nobility: Knights who have been given a keep and grant of land to administer. They have their own peasants and men-at-arms, and may even take sworn swords. Landed knights are sworn to fight for the lord who holds dominion over their land. While the wealthiest knights manage more land than the poorest lords, landed knights do not have the authority to deliver law and justice in their land. Rather, they must appeal to their liege lord.
Landed knight is a rare rank in the north and is almost nonexistent on the Iron Islands, because knighthood is culturally linked with the Faith of the Seven, which is not widely practiced in those lands.
Commoners
Commoners or smallfolk are the bottom of the social structure. They do not own lands or titles; they work the land of their lords, and do not have a say in their own governing. While this may seem similar to slavery, the difference is that commoners own themselves, and can make appeals to their local lord regarding violations of the law or general disagreements between parties; they are recognized as having a right to fair and just treatment by the nobility and society in general. Most Houses have laws protecting the local population from abuse or mistreatment, even by members of the nobility. However, those laws differ and are enforced in varying degrees, mostly depending on the disposition of the local lord.
Many of the tradesmen and craftsmen belong to guilds, such as the Alchemists' Guild.
There is little social mobility; odds are that if you are born a commoner, you will never be able to rise above commoner status. However, it does happen, and there several examples of people who have managed it. Varys was a common-born slave, and rose to be the spymaster of the Seven Kingdoms. Dunk was born a commoner in Flea Bottom, yet he was able to rise to be a member of the Kingsguard.
Terms
Warden, commanders who exercise military functions for the north, east, south, and west of the Seven Kingdoms. There are also wardens for smaller geographic locations, such as the Wyman Manderly being Warden of the White Knife.
Liege, the primary lord of a vassal who holds by military tenure. The liege lord and vassal each have responsibilities to one another; the vassal must remain loyal to the liege lord above any other lords, while the liege is the vassal's principal protector.
Vassal, a person granted the use of land, in return for rendering homage, fealty, and usually military service or its equivalent to a lord or other superior. They are frequently referred to as "bannermen".