When you think of crude oil, the first thing that probably comes to your mind is the black liquid that is pumped out of a reservoir. Or you might be thinking of the liquid you pump into your car, which you notice is a bit more expensive than it was a decade or even a week ago. The definition of crude oil is confusing and variable and has been made even more confusing by the introduction of other terms that add little, if anything to petroleum definitions and terminology. Actually, until the mid-1800s, this vast untapped wealth lay mostly hidden below the surface of the earth. Some oil naturally seeped to the earth's surface and formed shallow pools that were used as a source of medicinal liquids, illuminating oil, and, after evaporation of the volatile components, as a caulking for boats and a building mastic. For centuries, demand was limited but better refining techniques and surging demand for kerosene and lubricants in the late 19th century changed this. Today, crude oil is the major source of fuel used by people today. In this course, we will go back to petroleum’s verbal roots, through its initial uses to its role in society today and the major oil companies that distribute it.