The French revolution was a reaction to bad economic circumstances hurting the poor in the nation, as well as the limited opportunities for an emerging middle class in France, and finally due to perceived mismanagement on rulers. Basically, the problems in the nation were such that the three estates, clergy, nobility, and commoner were brought together to solve them. However, there was a conflict between these three estates and their power and so on. Because of that, the third estate, the commoners, seeing this as an opportunity to solve their problems, and to reorganize France under the ideology of the Enlightenment(which included the equality of all people) organized into a revolutionary force that tore apart French society.
Well, because the French revolution was so revolutionary, re-organizing the people after this revolution was painful. It involved a lot of blood as various powers vied for control, until finally the general Napolean Bonaparte organized the country as a "republic" which was really a state ruled by Bonaparte. This state then waged a massive war with other nations owing successes to Napolean's strategic mind, as well as the ability of the French to use a larger portion of their population for warfare due to the organization of their society.
Eventually Napoleanic rule was crushed and a new nobility was put into power.
The entire ordeal is often considered a lesson against revolutionary change. As, even though changes can work, the major fruit of the French revolution ended up being a lot of bloodshed more than almost anything else.