Definition:
An oil is any non-polar chemical substance that is a viscous liquid at room temperature and is both hydrophobic (does not mix with water, literally "water-shy") and lipophilic (mixes with other oils, literally "fat-loving").
Oils have a high carbon and hydrogen content and are usually flammable and surface active. Most oils are unsaturated lipids that are liquid at room temperature.
Use:
The consumption of oil is still rising. In 2017, it was almost 100 million barrels (159 litres) per day worldwide. For years, road transport has accounted for the largest share of consumption: worldwide, it was 42 percent in 2014, in the EU consumption is even slightly higher. Air transport and maritime shipping also account for more than ten percent. Crude oil is playing an ever smaller role in heating buildings; this is being replaced by electricity or other energy options.
Consume of oil:
Oil has historically been the world's most used energy source. The US has been the biggest oil consumer for the past two decades followed by China, which has been consuming increasingly more oil, especially gasoline. Oil is particularly useful as a fuel because of its high energy density.
Crude oil is processed at petroleum refineries to make many different products, such as motor gasoline, distillate fuel oil, hydrocarbon gas liquids, and jet fuel. More than two-thirds of finished petroleum products consumed in the United States are used in the transportation sector. 33