Since there isn't anything specific that is being asked about Louis XVI, I will do my best to give you a rundown of important information regarding who he was and his legacy.
Louis XVI was born on August 23rd, 1754 and was the eventual successor to the French throne after his grandfather, Louis XV. At the age of 16, he married Marie Antoinette, the daughter of the Austrian monarch, to finalize an alliance between the two monarchs.
Louis XVI had to endure financial crisis in France after being bankrupt from assisting the colonists during the American Revolution as well as many harsh growing seasons agriculturally. He received harsh criticism for the lavish lifestyle he and his wife lived at the Palace of Versailles.
Louis XVI is best known for being the monarch during the French Revolution. Louis tried to appease the Third Estate, (approximately 97% of the population where most were living in extreme poverty) by calling a meeting of the Estates General in 1789. This meeting was a gathering of representatives of all three estates, but failed miserably when the angry third estate declared itself the National Assembly and created its own constitution.
Once word reached people in Paris, an angry mob of Parisians stormed the old armory that served as a prison known as the Bastille, killing the warden and releasing the prisoners. This marked the beginning of the French Revolution and the beginning of the end of the rule of Louis XVI.
Outside forces from Austria and Prussia began to advance into France to restore control to Louis, which radicalized the newly appointed National Convention. Under the charge of Maximilian Robespierre, Louis XVI was executed by the new killing machine known as the guillotine. The National Convention declared that France was a republic and eventually Marie Antoinette was put to death as well.