On this Wikipedia the language links are at the top of the page across from the article title. The general definition oil grades explained oil includes classes of chemical compounds that may be otherwise unrelated in structure, properties, and uses. Oils may be animal, vegetable, or petrochemical in origin, and may be volatile or non-volatile. Organic oils are produced in remarkable diversity by plants, animals, and other organisms through natural metabolic processes.

Lipids can be classified by the way that they are made by an organism, their chemical structure and their limited solubility in water compared to oils. Crude oil, or petroleum, and its refined components, collectively termed petrochemicals, are crucial resources in the modern economy. Several edible vegetable and animal oils, and also fats, are used for various purposes in cooking and food preparation. In particular, many foods are fried in oil much hotter than boiling water. Oils are applied to hair to give it a lustrous look, to prevent tangles and roughness and to stabilize the hair to promote growth. Oil has been used throughout history as a religious medium.

It is often considered a spiritually purifying agent and is used for anointing purposes. Color pigments are easily suspended in oil, making it suitable as a supporting medium for paints. The oldest known extant oil paintings date from 650 AD. Oils are used as coolants in oil cooling, for instance in electric transformers.