Final answer:
The Bourgeoisie or Middle Class of the Third Estate represented the educated and economically upwardly mobile segment of French society, including professionals and merchants. Heavily taxed yet politically marginalized, they were catalysts for change during the French Revolution, seeking to challenge the tax-exempt, land-holding aristocracy and clergy.
Step-by-step explanation:
The Bourgeoisie or Middle Class of the Third Estate in pre-revolutionary France was a group that consisted of merchants, bankers, doctors, lawyers, and other professionals who often possessed wealth that could rival the nobles but were not of noble birth. Unlike the First and Second Estates, which included the clergy and nobility respectively, the Bourgeoisie were subjected to taxation and lacked the political privileges held by the other two estates. The Bourgeoisie were key players in the ensuing French Revolution of 1789, as their exclusion from political power and the heavy tax burden they shared with the lower segments of the Third Estate fueled discontent and a demand for reform.
The aristocracy led a life of leisure and luxury, owning a hefty portion of the country's wealth and almost all of its political power, creating a stark contrast to the lives of the Bourgeoisie and the rest of the Third Estate. With urbanization and the advent of industrialism, the Bourgeoisie experienced growth, amassing wealth and influence in the burgeoning city economies, which ultimately led to their challenging the existing social order during the French Revolution.