We all know that products such as motor oil and gasoline are derived from crude oil. However, many people are unaware that crude oil also serves as the raw material for a wide range of everyday products, including clothing, vitamin capsules, tyres, and numerous synthetic materials. Crude oil is found deep beneath the earth's surface, both on land and under the ocean. It is formed from the remains of plants and animals that lived millions of years ago and were gradually subjected to intense heat and pressure over long periods of time. Typically blackish in colour, crude oil has a distinctive odour due to the presence of small quantities of sulphur- and nitrogen-containing compounds. Crude oil exists in different grades, each having a unique composition determined by the original organic material and the geological characteristics of the surrounding soil and rock formations. Based on density, crude oil may be classified as light or heavy. Petroleum, also known as crude oil, is a naturally occurring, oily and flammable liquid found in underground reservoirs. It is composed mainly of hydrocarbons, along with trace amounts of nitrogenous and sulphur-based compounds. The term "petroleum" is derived from the words petro, meaning rock, and oleum, meaning oil. Natural oil seeps and pools have been known for thousands of years. Historical records indicate that the Chinese extracted oil from wells as deep as 800 feet using bamboo pipes as early as 347 AD, primarily to evaporate brine and produce salt. American Indians used petroleum for medicinal purposes, while ancient Persians, Macedonians, and Egyptians applied it for waterproofing ships. The Babylonians used asphalt as early as the 8th century to construct city walls, towers, and roads.