Humans have known oil since ancient times. Oil deposits found on the surface were used for centuries for waterproofing and fuel purposes. But it was not until the coming of the Industrial Revolution that civilizations began to form a dependence on petroleum products. The widespread use of oil for fuel, lubrication, and other purposes led to a search for larger supplies. In the mid 1800s, the first oil wells were drilled, marking the beginning of a tremendously important and profitable industry. Today, with the world's oil supplies dwindling and the demand for oil constantly rising, oil is a more valuable resource than ever.