The word “petroleum” derives from the Latin words “petro” (rock) and “oleum” (oil).

Petroleum is defined as a mixture of a large number of different hydrocarbons, in gaseous, liquid and solid states, with molecular compositions ranging from one to forty carbon atoms. It was originated by the decay of marine phytoplankton through processes that differ in their length of time and their conditions of temperature and pressure.

Compounds included under this broad term are crude oil,  lease condensates, natural gas plant liquids and refined products obtained from the processing of crude oil.

Crude oil is found in underground reservoirs that usually also contain salt water and gas. It undergoes processes of fractionation and cracking to yield the following petroleum fractions: gas (C₁ to C₄₎, petroleum ether (C₅ to C₆), aviation and motor gasoline (C₇ to C₁₀), kerosene (C₁₁ to C₁₃), diesel oil (C₁₄ to C₁₈), heavy gas oil (C₁₉ to C₂₅), lubricating oils (C₂₆ to C₄₀), paraffin and asphalt.

The intensive use of petroleum began in late 19^th century, and by the decade of 1940 it had already displaced coal as the world's main source of energy.

Petroleum is mainly used in transportation, industry, electric generation and commercial and domestic uses.

The petroleum industry is one of the world’s largest and it constitutes a pillar of global economy. I can be divided into four major branches: Production (exploration and extraction of crude oil), Transportation (crude oil from the oil field to refineries, and products from the refineries to consumers), Processing (crude oil refining into derived products), and Distribution (to individual consumers through gas service stations or directly to industries, transportation and power plants).

 NOTE: on some graphics, crude oil and natural gas plant liquids (NGPL) are displayed separately; on others, both fuels are displayed together under the broader term “petroleum”.

Petrochemical News Information from Platts.
Crude Oil Prices from Platts.