Olives are the fruit of the olive tree (Olea europaea), almost always cured or brined before eating since raw olives are intensely bitter. Native to the Mediterranean basin and the Middle East, the olive tree has been cultivated there for thousands of years, with Spain, Italy, Greece, and Turkey the leading producers today, alongside a smaller California industry. Green olives are picked unripe and taste more bitter and firm; black olives are left to ripen fully, or are oxidized, and are milder and softer. Cured olives underpin Mediterranean, Middle Eastern, and North African cooking, appearing in Greek salads, Italian pasta sauces, Spanish tapas, mezze platters, and tagines, and pair naturally with garlic, rosemary, lemon, tomatoes, and salty cheeses like feta. They are eaten as a snack, used as a garnish, or pressed for olive oil.