The steam engine is a device that uses steam to generate power. Water, heated by burning fuel (usually coal or wood), turns to steam. The steam is contained in a chamber where it builds up pressure, causing a piston to move. The piston drives a turbine, the rotation of which produces power which can be used for such purposes as producing motion or generating electricity. The early principles of this device were understood as early as the late 17th century, but it wasn't until 1769 that Scottish engineer James Watt patented a practical design for what was to become the basis for the modern steam engine. The invention of the steam engine led to a number of landmark developments, including the steam locomotive and the earliest examples of automobiles. Steam engines remains the chief means of motive power in the transportation industry until the invention of the more powerful and compact internal combustion engine. Steam turbines are still in use today in a number of applications including the generation of electrical power.