Crude oil, often simply called "crude," is an unrefined petroleum product composed of hydrocarbon deposits and other organic materials. It is a liquid found underground that can be refined to produce various fuels, including gasoline, diesel, and jet fuel, as well as other products like plastics and chemicals. Classification: Based on its specific gravity (API gravity) and sulfur content, crude oil can be classified into: Light or Heavy: Determined by its API gravity with light crude oil being less dense and, therefore, more valuable than heavy crude oil. Sweet or Sour: Based on its sulfur content. Sweet crude has less than 0.5% sulfur, while sour crude has a higher sulfur content. Physical Characteristics: Color varies from yellow to black. Viscosity can range from water-like to thick and tar-like. Distinctive odor, often pungent. Applications: Fuel Production: Main source for gasoline, diesel, kerosene, and jet fuel after refining. Petrochemicals: Base for manufacturing chemicals, plastics, synthetic materials, and more. Lubricants: Processed to produce motor oil, grease, and other lubricating products. Asphalt: Used in road construction. Storage & Handling: Crude oil is typically stored in large tanks or transported in pipelines, tankers, or rail cars. Proper care is needed during transportation to prevent spills and environmental contamination. Note: Crude oil's quality and characteristics can vary widely based on its geographical origin and the conditions under which it was formed. Before refining or using, a detailed analysis is usually performed to understand its composition and how best to process or utilize it.