From The Art and Popular Culture Encyclopedia
The Third Estate was the generality of people which were not part of the other Estates of the realm.
The Third Estate comprised all those not members of the above and can be divided into two groups, urban and rural. The urban included the bourgeoisie 8% of France's population, as well as wage-laborers (such as craftsmen). The rural includes the peasantry, or the farming class (about 90% of the population). The Third Estate includes some of what would now be considered middle class—e.g., the budding town bourgeoisie. What united the Third Estate is that most had little or no wealth and yet were forced to pay disproportionately high taxes to the other Estates.