Happy Bastille Day!
Explanation that even an American can understand is from Bryback Manor website:
Bastille Day is a national holiday in France. It is very much like Independence Day in the United States because it is a celebration of the beginning of a new form of government.
At one time in France, kings and queens ruled. Many people were very angry with the decisions made by the kings and queens.
The Bastille was a prison in France that the kings and queens often used to lock up the people that did not agree with their decisions. To many, it was a symbol of all the bad things done by the kings and queens. So, on July 14, 1789, a large number of French citizens gathered together and stormed the Bastille.
Just as the people in the United States celebrate the signing of the Declaration of Independence as the beginning of the American Revolution, so the people in France celebrate the storming of the Bastille as the beginning of the French Revolution. Both Revolutions brought great changes. Kings and queens no longer rule. The people rule themselves and make their own decisions.