Although the genre of the Canterbury Tales as a whole is a "frame narrative," the General Prologue to the Canterbury Tales is an example of "Estates Satire," a genre which satirizes the abuses that occur within the three traditional Estates into which medieval feudal society was traditionally divided. Referring to the hierarchal structure of the medieval society, the Three Estates Model establishes the shape of the society by dividing it into three main groups: the ecclesiastical (clergy=the ones who prayed), the nobility (the ones who ruled and fought), and the commoner (the ones who laboured). It was common for aristocrats to enter the Church and thus shift from the second to the first estate. In addition to belonging to the three estates, women were further categorized according to three specifically "feminine estates": virgin, wife and widow.
The rigid division of society into the three traditional "estates" begins to break down in the later Middle Ages. By the time of Chaucer (mid-fourteenth century), we see the rise of a mercantile class (mercantile = merchants) in the cities, i.e. an urban middle-class, as well as a new subdivision of the clergy: intellectuals trained in literature and writing (and thus "clerics" like Chaucer's Clerk), but who were not destined to a professional career within the Church.
Chaucer takes care to include representatives of all three traditional "male"and "female" estates (the Wife of Bath represents both "wife" and "widow," while the Prioress, a nun, is presumably a virgin). There an idealized portrait of each of the traditional (male) "estates": the “Parson”, the “Knight”, and the “Plowman”. There exist also the portraits representing two new groups that were gaining prominence in the fourteenth century: the middle class and intellectuals: the "Merchant" and the "Clerk"..