Olive oil is a liquid fat obtained by pressing whole olives, the fruit of the olive tree, Olea europaea, a traditional tree crop of the Mediterranean Basin. The olive tree is one of the oldest cultivated trees in human history, with evidence of olive oil production dating back to at least 4500 BCE in the Levant region. The scientific name Olea europaea means "European olive" in Latin, though the tree's origins are believed to lie in the eastern Mediterranean.
The olive tree is an evergreen that can live for hundreds or even thousands of years — some specimens in the Mediterranean are estimated to be over 2,000 years old. The largest producers of olive oil are Spain, Italy, Greece, Turkey, Tunisia, Morocco, and Portugal, with the Mediterranean region accounting for approximately 95% of global production. World annual olive oil production fluctuates between 2.5 and 3.5 million metric tonnes, with Spain alone producing approximately 40-50% of the global supply.
The production of olive oil begins with the harvesting of olives, typically between October and January in the Northern Hemisphere. The olives are washed, crushed into a paste (traditionally using granite millstones, now typically using stainless steel hammer mills), and the paste is slowly mixed (malaxed) to allow small oil droplets to coalesce.
The oil is then separated from the paste and water using hydraulic presses (traditional method) or horizontal centrifugal decanters (modern method). Virgin olive oil is produced entirely by mechanical means without the use of chemical solvents or excessive heat.
Olive oil is graded according to strict international standards. Extra virgin olive oil (EVOO) is the highest quality grade, obtained from the first pressing with a free acidity of no more than 0.8%, no sensory defects, and specific organoleptic (taste and aroma) qualities. Virgin olive oil has a maximum acidity of 2.0%. Refined olive oil is produced from lower-quality virgin oils that have undergone chemical refining. "Olive oil" (or "pure olive oil") is a blend of refined and virgin olive oils.
The historical significance of olive oil in Mediterranean civilisation is profound. In ancient Greece, olive oil was used for cooking, lighting, personal grooming, medicine, and religious ceremonies — Olympic athletes anointed themselves with olive oil, and victors were crowned with olive wreaths. In ancient Rome, olive oil was essential to the economy. The olive branch has been a symbol of peace since antiquity. In Christianity, Judaism, and Islam, olive oil holds deep religious significance.
In modern food applications, olive oil is valued for its distinctive flavour profile — ranging from mild and buttery to robust and peppery depending on variety, terroir, and harvest timing. Extra virgin olive oil is used in salad dressings, dipping, finishing dishes, and light sauteing. Olive oil is a cornerstone of the Mediterranean diet, which has been recognised by UNESCO as an Intangible Cultural Heritage and is associated with numerous health benefits including cardiovascular protection.
Nutritionally, olive oil is composed predominantly of oleic acid (omega-9, approximately 70-80%), with smaller amounts of linoleic acid (approximately 10%), palmitic acid (approximately 12%), and stearic acid (approximately 2%). Extra virgin olive oil also contains significant amounts of polyphenols (oleuropein, hydroxytyrosol, oleocanthal), tocopherols (vitamin E), squalene, and phytosterols — bioactive compounds associated with anti-inflammatory, antioxidant, and cardioprotective properties.
Beyond food, olive oil is used in cosmetics and skin care (moisturisers, soaps, hair treatments), pharmaceutical preparations, traditional medicine, and religious ceremonies worldwide. Industrial applications include soap manufacturing (Castile soap is traditionally made from olive oil), textile processing, and bio-lubricant formulations.
Interesting facts about olive oil include: there are over 700 olive cultivar varieties worldwide; Spain has over 300 million olive trees; the ancient Greeks believed the olive tree was a gift from the goddess Athena; extra virgin olive oil contains oleocanthal, a natural anti-inflammatory compound with properties similar to ibuprofen; and archaeological evidence suggests that olive oil was used as early as 6000 BCE for lamp fuel.