Extra Virgin, includes grades known as Premium Extra Virgin and Extra Virgin oil, which will be labeled as one of the three depending on the acidity level. It is one of the most expensive and one of the highest in quality, so it is best used as a condiment for dressing foods and salads or as a dipping oil because of its excellent flavor. Although this oil can be used for baking, it is best not to heat this oil, as it will loose the higher quality flavor it contains.
Virgin olive oil, which includes Fine Virgin, Virgin, and Semi-Fine Virgin, depending on the natural acidity level, are less expensive but are still flavorful. Grades catagorized as extra virgin and virgin are cold pressed and are not refined in any way. The Fine-Virgin and Virgin are of a slightly higher quality and may be used in dressings and as dipping oils. While all three grades can be used in cooking or baking, the Semi-Fine Virgin is lower in quality and is an oil that is most often used for baking and sautéing foods.
The olive oil grade known simply as "Olive Oil" is a refined oil with virgin or extra virgin oil added. Generally, refined olive oil will have small quantities of extra virgin or virgin olive oil added to provide some pleasing characteristics to the appearance of the oil. The grade referred to as a refined olive oil contains very little color, aroma, or flavor and may be sold without additional processing. Also, some refined olive oils may be flavored with herbs or fruit flavors and sold as a specialty product. Depending on the producer, this type of oil may be labeled as "Olive Oil", "Pure Olive Oil", or "100% Olive Oil", indicating that no other types of oil have been added. The refined oils may also be labeled as "Mild Olive Oil" or "Light Olive Oil" referring to the flavor and not the calorie content of the oil. This grade of oil, which is considered as a lower grade of olive oil and thus, are less expensive, are widely used as oils for cooking and not dipping or dressings.
Olive oil is considered to be healthy because it contains a high concentration of monounsaturated fat, which researchers have identified as a fat that assists in reducing levels of LDL, or bad cholesterol in the human body. Olive oil can be stored in a dry, dark area of the kitchen and should not be exposed to excessive heat. Bottled oils can be kept for a year before they begin to lose their flavor.