The estates of society were established in the Middle Ages as the way the world was ordered. The king or queen held a position above all the estates. The first estate was the church and the clergy. The second estate was the nobility or ruling class. The third estate was the common people. As you note, the fourth estate emerged as the public media.
The fourth estate
The term Fifth Estate is any class or group in society other than the clergy (First Estate), the nobility (Second Estate), the commoners (Third Estate), and the press (Fourth Estate). It has been used to describe trade unions, the poor and organized crime. It can also be used to describe media that sees itself in opposition to mainstream (Fourth Estate) media. The term is different in origins and meaning from 'Fifth Column,' used to describe subversive or insurgent elements in a society. It's origins probably comes from the French Estates-General. And for all you bloggers out there, Media researcher Stephen D. Cooper argues that bloggers are the Fifth Estate.
the first estate often faced revolts from the other two estates
Third Estate was the generality of people which were not part of the other estates, or commoners. Bourgeoisie were middle class.
goal of first estate was to maintain status quo, not be taxed and gain more power. That of second estate was same. That of third was to get greater power and require other 2 estates to pay taxes
There were 3 estates: the third estate was the bourgeoisie. They represented 97% of all inhabitants of France. There other two estates (the first and second) were the nobility and the clergy (the representatives of the church).
They insisted that all three estates meet together and that each delegate have a vote. This would give the advantage to the Third Estate, which had as many delegates as the other two estates combined
By calling the Estates-General Louis the XIV would be at a disadvantage because it would give more power to the 1st Estate and the 2nd Estate. He would be losing power and he had no reason to call on the Estates-General. Louis the XVIII had to call on the Estates-General because the country was about to go bankrupt and he had no other choice but to call on the Estates-General and ask them for a loan.
the "clergy" (mostly corrupted at the time
The members of the Third Estate were arguing about the process for the Estates-General. The king's ministers had intended that the three estates meet and vote separately, with each estate having one vote. Instead, the Third Estate insisted that the three estates meet as one body, and that voting be by head so that each person have one vote (the Third Estate had as many members as the other two estates combined). When the deadlock over procedure could not be resolved, the members of the Third Estate declared themselves to be the only legitimate representative body, and renamed themselves the "National Assembly". They then vowed never to disband until they had written a constitution for France. They did this on 20 June 1789. The Third Estate invited the members of the other two estates to join them as part of the National Assembly, which they eventually did.
It was divided into three Estates each theoretically equal to each other. The First Estate was the Catholic clergy, the Second Estate and all others were in the Third Estate.
It was called to deal with Economics and was converted by the Third Estate as a call for an end to the absolute Monarchy and a call for representation in the government.