Olive oil is pressed from the flesh of Olives.

There are two main types of olive oil, refined and unrefined, and there are a few different grades of olive oil. Exhaustively, below, the first two items are unrefined and the rest are refined.

• Extra virgin olive oil
• Virgin olive oil
• Refined olive oil
• Pure olive oil
• Olive pomace oil

Virgin oil has slightly higher acidity than extra virgin oil. Refined and pure oil are made by refining virgin olive oils. Finally, pomace oil is made from oil extracted from the olive pit and is only used for cooking: it has a higher smoke point than unrefined olive oils like virgin and extra virgin.

In ancient Greece olive oil was an important export, as important as wine and pottery, and its utility made olives a staple crop in the Mediterranean. Olive oil was used as food, fuel and as a beauty cosmetic. It was given to athletes as trophies celebrating their victories (it was often quickly re-sold by these athletes), who themselves annointed their bodies with it traditionally before competition.

In the Jewish story of the miracle of Hanukkah, also known as the Miracle of the cruse of oil, a night's worth of olive oil burned in a menorah for 8 nights. After the defiling of the second temple in Jerusalem by the Greeks, returning Jewish soldiers who'd been fighting the Greeks sought to purify and rededicate the temple:

As the Maccabees searched for pure oil to light the menorah with, they found just one cruse of pure oil which still had the seal of the High Priest, the symbol of pure oil. This cruse contained just enough pure oil to keep the menorah lit for one day. In order to make pure oil however, individuals making the oil must be in a state of spiritual purity. Being soldiers returning from the battlefield, the Maccabees were deemed impure, and therefore could not make pure oil. Since the process of ritual purification after touching a corpse lasts seven days, the Maccabees could only produce additional pure oil after eight days: seven days of becoming pure including one day, once pure, to actually make the oil. Therefore, the Maccabees would have been unable to light the Menorah for seven days before the completion of new pure oil. Miraculously, the one cruse of oil had lasted for all eight days, and by that point new pure oil was ready.

Today olive oil is sold at the grocery store. Amid canola and vegetable oil it is not notable to the passerby except for being priced moderately higher. There are grades of olive oil and they are used for different things. Extra virgin olive oil (EVOO) and virgin olive oil are great for dipping. Both can be rich in flavor served cold with bread, balsamic, salt and pepper.

The gentle oils like EVOO and virgin olive oil denature when severe heat is applied to them as they have a low-ish smoke point.

Refined, pure and pomace oils have a much higher smoke point. That means they are suitable for frying and searing things like steak and fish. Steak, especially, can demand high temperatures to sear. Olive oil can fry just as canola, vegetable and grapeseed oils can fry, provided you pick the one with an appropriate smoke point:

Some believe olive oil, particularly extra virgin olive oil (EVOO) is healthier than other oils. Yes, it's moderately healthier. But in the same breath you're likely to die from something else well before the canola oil does you in.