Why was the third estate frustrated with the old regime in France?

The Third Estate in France was frustrated with the old regime because they bore the brunt of taxation while having little political power or representation. Comprising the common people, including peasants, urban workers, and the bourgeoisie, they felt exploited by the privileges enjoyed by the First (clergy) and Second (nobility) Estates. This inequity fueled their discontent and desire for reform, ultimately leading to the French Revolution as they sought greater equality and rights within the societal structure.