Petroleum is vital to many industries, and is of importance to the maintenance of industrial civilization itself, and thus is a critical concern for many nations. Oil accounts for a large percentage of the world’s energy consumption, ranging from a low of 32% for Europe and Asia, up to a high of 53% for the Middle East. Other geographic regions’ consumption patterns are as follows: South and Central America (44%), Africa (41%), and North America (40%).
The world consumes 30 billion barrels (4.8 km³) of oil per year, with developed nations being the largest consumers. The production, distribution, refining, and retailing of petroleum taken as a whole represents the world's largest industry in terms of dollar value.
Governments provide a heavy public subsidy to petroleum companies, with major tax breaks at virtually every stage of oil exploration and extraction, including for the costs of oil field leases and drilling equipment.
The American Petroleum Institute divides the petroleum industry into five sectors:
- upstream (exploration, development and production of crude oil or natural gas)
- downstream (oil tankers, refiners, retailers and consumers)
- service and supply