Answer:
The Tennis Court Oath or Serment du Jeu de Paume in French was a oath taken by the members of the third estate in France which is an important event prior to the French Revolution.
At that time France was combined of three society, which are Clergy, nobility and the Third estate. The third estate used to represents the common people of the France. These three groups used meet at the Estate General time to time. On a convention in 1789 the Third estate groups declared themselves as the National assembly as they out numbered the other groups. But on 20th June they find themselves locked in the conference room and realized the king is going to prevent them. Based on the situation the 576 members of 577 members went to a nearby tennis court and took oath that whatever the situation, they will not separate and segregate until the the written constitution is formed.
Their vow to this oath made the king to order the Clergy and the Nobility to join them in the assembly. This event made a mark for the third estate that the decision making power of the nation is not only held by the king. The political parties are the representative of the people rather than King.
This event led the French Revolution one step ahead.
Step-by-step explanation: