The Terror is very aptly named. Thousands of innocent civilians were tortured and killed, sometimes for their political opinions or actions, but often for little reason whatsoever. This killing was usually through the work of the guillotine, or 'Madame Guillotine' as it was called.
The terror started on September 5, 1793 when the National Convention voted to implement terror measures to repress revolutionary activities. The ensuing "Reign of Terror" lasted until the spring of 1794, and killed 35,000 to 40,000 people.
The White Terror took place in 1815 following the return of King Louis XVIII to power; people suspected of having ties with the governments of the Revolution and Napoleon were arrested and executed.