Oil is a nonpolar, hydrophobic, and lipophilic liquid composed primarily of hydrocarbons, typically flammable and unsaturated, with viscosity that varies by temperature. It comes from diverse sources: plant and animal oils (like cooking oils, tallow, and drying oils for paints), petroleum-derived oils from ancient fossilized zooplankton and algae (used as fuels and hydraulic fluids), and synthetic lubricants. The word "oil" traces back through Old French and Latin to the Greek elaion (olive oil) and even Mycenaean Greek e-rai-wo, with the earliest English usage appearing around 1300 in Anglo-Norman. Historically, oil has served as a spiritual medium, particularly as holy anointing oil in Judaism and Christianity, symbolizing purification. Commercially, fats are crucial precursors to soaps and food ingredients, while petroleum oils power heating and machinery, making oil indispensable across industries and cultures.