The critters and algae that are now crude oil lived millions to hundreds of millions of years ago. After they died and their remains were subjected to pressure from the rocks above and heat from the inner earth, the mess cooked for a few million years or so and eventually became crude oil. Because it takes so long for crude oil to develop, it's a non-renewable resource. Once oil is gone, it's gone. Analysts for the American Petroleum Institute projected that the world's oil supply will allow production to continue at today's rates at least to the year 2050.
New technology is the major reason the oil deadline keeps getting pushed back.
The need for new oil is fueled by the world's dependence on the substance for everything from gasoline to the clingy plastic that wraps our sandwiches. The U.S. Energy Information Administration reports that the United States used 18.6 million barrels each day in 1997. A barrel equals 42 gallons, so Americans used 781 million gallons of crude oil per day in 1997. The EIA also calculated that in 1997 Americans used 25 barrels of oil per person per year. That means every man, woman and child used more than 1,000 gallons of crude oil that year, the rough equivalent of eighteen 55-gallon drums of crude oil for each person.