Overview Crude oil is a liquid hydrocarbon mixture produced from underground reservoirs and refined into fuels and petrochemical feedstocks. In commodity markets, it is typically priced by benchmark grades such as Brent, West Texas Intermediate, and Dubai/Oman, with prices quoted in U.S. dollars per barrel. A price index for crude oil aggregates movements across benchmark grades or representative spot and futures contracts into a single index number, allowing comparison over time and across markets. One barrel equals 42 U.S. gallons, and the standard trading unit is the barrel, though physical cargoes are also traded in metric tons in some regions. Crude oil is the principal input for gasoline, diesel, jet fuel, heating oil, marine fuel, lubricants, asphalt, and many petrochemicals. Its market importance comes from its dual role as both an energy source and a chemical feedstock. Because refining can shift output among products, crude oil prices transmit through the broader energy complex and into transportation, manufacturing, agriculture, and household energy use. Supply Drivers Crude oil supply is shaped by geology, reservoir decline, extraction technology, and transport infrastructure. Production is concentrated in regions with large sedimentary basins, including the Middle East, North America, Russia, and parts of Latin America and Africa. Conventional fields often exhibit natural decline after peak output, while shale and tight oil require continuous drilling to offset steep well declines. Offshore projects and oil sands typically involve high capital costs and long lead times, which make supply slower to respond to price changes. Weather and climate affect supply through hurricane disruption in offshore areas, freeze-offs in cold regions, and seasonal maintenance constraints. Political stability, export logistics, pipeline capacity, port access, and refinery compatibility also shape deliverability. OPEC and other coordinated producers influence supply by managing output within the limits of spare capacity and reservoir behavior, but physical constraints remain central. Because oil is storable, supply disruptions can be buffered temporarily, yet prolonged outages or bottlenecks still move prices sharply. Demand Drivers Crude oil demand is driven mainly by transportation, petrochemicals, industrial heat, and some power generation. Road fuels, aviation fuel, diesel for freight, and marine bunkers account for much of consumption, so demand is closely tied to freight activity, passenger travel, and industrial production. Petrochemical demand links crude oil to plastics, synthetic fibers, solvents, and fertilizers through naphtha and other refinery streams. In many uses, oil competes with natural gas, coal, biofuels, electricity, and, in transport, efficiency improvements and alternative drivetrains. Demand is seasonal in many regions because gasoline use rises with driving activity and heating oil demand increases in colder periods. Income growth tends to raise oil consumption through higher mobility, freight, and goods production, though efficiency gains moderate the effect over time. Refinery configuration also matters: light, sweet crudes and heavy, sour crudes are not perfect substitutes because different refineries are built for different feedstocks. Environmental standards and fuel specifications influence product slates and can shift demand among crude grades rather than eliminate oil use entirely. Macro and Financial Drivers Crude oil is usually priced in U.S. dollars, so exchange-rate movements affect purchasing power for non-dollar buyers and can influence global demand. Because oil is storable, futures curves reflect the cost of carry: storage, insurance, and financing. When inventories are ample, deferred contracts often trade above nearby contracts; when supply is tight, nearby prices can exceed deferred prices. Interest rates matter through financing costs for inventories and capital-intensive upstream projects. Oil prices often correlate with broader industrial activity and can move with expectations for manufacturing, freight, and travel demand. They also interact with inflation because energy costs feed into transport, production, and consumer prices. As a result, crude oil can behave as both a cyclical commodity and a partial inflation pass-through mechanism, though it is not a pure financial hedge. Related Commodities Natural gas is a close substitute in power generation, industrial heat, and some petrochemical uses, though transport fuels rely far more on oil. Refined products such as gasoline, diesel, and heating oil are direct downstream outputs and often move with crude feedstock costs. Coal can substitute in some industrial and power applications, while biofuels such as ethanol and biodiesel compete in transportation blends and can alter marginal oil demand.