Peak Oil
The supply and production rate of crude oil follows a bell-shaped curve. Oil is increasingly plentiful on the upslope of the bell curve, and increasingly scarce & expensive on the downslope. The peak of the curve is the point at which oil production reaches the highest amount it ever has and ever will.
A bell-shaped production curve, as suggested by M. King Hubbert in 1956.
Because the production curve for oil is parabolic, there will be oil after the peak but production will drop in a world of increasing demand. The price of oil will continue to increase as the demand increases.