The French revolution in 1789 is considered one of the great turning points in the history of the western world. In many ways it was inspired by the American Revolution that began thirteen years previous, but its repercussions were far more wide-ranging and spectacular. In many ways, the 1789 french revolution changed the fate of the western world, laying the ground for the crumbling of the staid monarchical traditions of old Europe and paving the way for the industrial revolution and democratization of the continent and, as a result, much of the rest of the world.
The 1789 French revolution is significant because it marked the first time a European people revolted and successfully overthrew a sitting monarch with the goal of permanently replacing the monarchy. Previous revolutions had had more the shape, scope and ideals of a civil war with one faction fighting another for power. What made the 1789 french revolution different was that it was a war of ideas and ideals, something previously unseen and unimagined.
As for the causes and ideals, Wikipedia.com has an extensive look at the 1789 french revolution and lists them thusly:
There were also social and political factors, many of which involved resentments and aspirations given focus by the rise of Enlightenment ideals. These included resentment of royal absolutism; resentment by the ambitious professional and mercantile classes towards noble privileges and dominance in public life, as many of these classes were familiar with the lives of their peers in commercial cities in the Netherlands and Great Britain; resentment by peasants, wage-earners, and the bourgeoisie toward the traditional seigneurial privileges possessed by nobles; resentment of clerical advantage (anti-clericalism) and aspirations for freedom of religion, resentment of aristocratic bishops by the poorer rural clergy, continued hatred for Catholic control, and influence on institutions of all kinds by the large Protestant minorities; aspirations for liberty and (especially as the Revolution progressed) republicanism; and anger toward the King for firing Jacques Necker and A.R.J. Turgot (among other financial advisors), who were popularly seen as representatives of the people.
All of the above was exacerbated by France’s staggering national debt at the time, a subsistence crisis in which many of the country’s poor were starving, and of course Louis XVI‘s total inability and unwillingness to address any of those concerns.
While those who revolted were in many ways justified in doing so, it’s important to remember that the French revolution in 1789 didn’t create the democratic meritocracy many of the protagonists hoped for, but rather an even more oppressive dictatorship led by Napoleon Buonoparte.