Olive oil is a fruit oil obtained from the olive (Olea europaea; family Oleaceae along with lilacs, jasmine and ash trees), a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps. Olive oil is much healthier than other sources of alimentary fat because of its high content of monounsaturated fat (mainly oleic acid) and polyphenols with a powerful antioxidant Hydroxytyrosol.

Over 700 million olive trees are cultivated worldwide, about 90% of those in the Mediterranean region. Most of global production comes from Southern Europe, North Africa and Middle East. Of the European production, 92% comes from Spain, Italy, Turkey, and Greece. Spain's production alone accounts for 40% to 45% of world production, which was 2.6 million metric tons in 2002. In 2006 Turkey accounted for over 25% of world production, this figure is similar to the province of Jaen production alone, in Spain, well known as the biggest olive groves in the world.

Retail grades in IOOC member nations
As IOOC standards are complex, the labels in stores (except in the U.S.) clearly show an oil's grade:

Extra-virgin olive oil comes from cold pressing of the olives, contains no more than 0.8% acidity, and is judged to have a superior taste. There can be no refined oil in extra-virgin olive oil.

Virgin olive oil has an acidity less than 2%, and judged to have a good taste. There can be no refined oil in virgin olive oil.

Pure olive oil. Oils labeled as Pure olive oil or Olive oil are usually a blend of refined olive oil and one of the above two categories of virgin olive oil.

Olive oil is a blend of virgin oil and refined oil, containing no more than 1.5% acidity. It commonly lacks a strong flavor.

Olive-pomace oil is a blend of refined pomace olive oil and possibly some virgin oil. It is fit for consumption, but it may not be called olive oil. Olive-pomace oil is rarely found in a grocery store; it is often used for certain kinds of cooking in restaurants.

Lampante oil is olive oil not used for consumption; lampante comes from olive oil's ancient use as fuel in oil-burning lamps. Lampante oil is mostly used in the industrial market.
It is believed that history from Portuguese olive oil and olives goes bas probably back to the Bronze age and certainly goes back to the time of Romans. Since its foundation olive oil has been part of Portuguese cuisine.

The olive trees can live thousands of years. In the Algarve there is a tree with an estimated age of 2000 years.
Approximately 4/5 of olive trees grown in Portugal are from Galega olive cultivar.
The distinctive character from Portuguese olive oil is due to the Galega olives. There are 7 regions with European recognition of locality and content and stamp or origin, known as DOP: "Azeite de Moura", "Azeite de Trás-os-Montes", "Azeites do Ribatejo", "Azeites do Norte Alentejano", "Azeite da Beira Alta", "Azeite da Beira Baixa" and "Alentejo Interior".
Quinta Dos Mattos, based in the Douro region, produces an extra virgin olive oil, cold pressed and unfiltered. Deliciously fresh, herby and nutty with zingy green fruit; lighter, tarter (acidity is 0.2% ) and delicate fruitness
The perfect health of the olive groves here is achieved by fighting birds and diseases and especially the olive fly (dacus oleae), using decoy methods. The collection of the olives is done by beating the trees with staffs, taking care that the fruit is at the right stage of maturity, and transport of the harvest is done using sacks made from vegetable fibers, holding up to 50 kilos. Processing always takes place within 3 days at oil presses in the prefecture of Galafura, Peso da Regua, Douro Valley, maintaining a temperature of less than 30 degrees Celsius throughout all stages of production.