The 18th century lasted from 1701 to 1800 in the Gregorian calendar.
However, Western historians have occasionally defined the 18th century otherwise for the purposes of their work. For example, the "short" 18th century may be defined as 1715–1789, denoting the period of time between the death of Louis XIV of France and the start of the French Revolution with an emphasis on directly interconnected events.
To historians who expand the century to include larger historical movements, the "long" 18th century  may run from the Glorious Revolution of 1688 to the battle of Waterloo in 1815 or even later.
During the 18th century, the Enlightenment culminated in the French, Haitian and American revolutions. Philosophy and science increased in prominence. Philosophers were dreaming about a better age without the Christian fundamentalism of earlier centuries. This dream turned into a reality with the French Revolution, although it was later compromised by excess of the terror ofMaximilien Robespierre. At first, the monarchies of Europe embraced enlightenment ideals, but with the French revolution they feared losing their power and joined wide coalitions with the counter-revolution.
The Ottoman Empire was undergoing a protracted decline, as it failed to keep up with the technological advances in Europe. The Tulip period symbolized a period of peace and reorientation towards European society, after victory against a burgeoning Russia in 1711. Throughout the century various reforms were introduced with limited success.
The 18th century also marked the end of the Polish-Lithuanian Commonwealth as an independent state. The once powerful and vast kingdom, that was once able to conquer Moscow and defeat the great Ottoman armies, collapsed under numerous invasions. Its semi-democratic government system was not efficient enough to rival the neighbouring monarchies of Prussia, Russia and Austria who divided the Commonwealth territories among them, changing the landscape of Central European politics for the next hundred years.
Great Britain became a major power worldwide with the defeat of France in the Americas in the 1760s and the conquest of large parts of India. However, Britain lost much of its North American colonies after the American Revolution, which was actively helped by the French. The industrial revolution started in Britain around the 1750s with the patenting of the steam engine. Despite its modest beginnings in the 18th century, it would radically change human society and the environment.