Olive Oil
What is olive oil? Olive oil is fat obtained from the fruit of the Olea Europaea (olive tree) from the Mediterranean region.
Olive oil tastes great when its fresh. But olives are highly perishable, and their complex flavor degrades quickly, which makes producing and handling , a top notch oil time-sensitive, labor-intensive, and expensive!
Olive oils are graded by production method, acidity content, and flavor. The International Olive Oil Council (IOOC) sets quality standards that most olive-oil-producing countries use, but the United States does not legally recognize these benchmarks. Instead, the U.S. Department of Agriculture uses a different system that was set up before the IOOC existed. However, American olive growers and oil importers are encouraging the USDA to adopt standards similar to those of the IOOC.
Olive oil is grown in many different countries, here are some of the best Olive Oils in the world
Spanish olive oil is typically golden yellow with a fruity, nutty flavor. 
Spain produces about 45 percent of the world’s olive supply.
Italian olive oil is often dark
green and has an herbal aroma and a grassy flavor. Italy grows about 20 percent of the world’s olives.
Greek olive oil packs a strong flavor 
and aroma and tends to be green. Greece produces about 13 percent of the world’s olive supply.
French olive oil is typically pale in color and has a milder flavor than other varieties.
Californian olive oil is light in color and flavor, with a bit of a fruity taste.
Types of Olive Oils
Extra virgin ( best for salads , dipping in bread, etc)
Premium extra virgin
Extra virgin
Virgin ( good for salads, can use in cooking)
Fine Virgin
Virgin
Semifine virgin (not for uncooked sishes, ie salads)
Olive Oil
Pure Olive Oil
Refined olive oil
Lite Olive Oils
These oils do not mean that they contain less fat or are for diets! They just go through an additional filtration process to remove most of the natural color, aroma and flavor. This makes this type perfect for all types of cooking and baking.
Acidity Levels %
Premium extra-virgin olive oil 0.225
Extra-virgin olive oil 0.8
Fine virgin olive oil 1.5
Virgin olive oil 2.0 or less
Semifine virgin olive oil 3.3 (no higher)
Refined oil oil Greater than 3.3
How to Store Olive OIl
Unlike wine, oil does not improve with age. As olive oil gets older, it gradually breaks down, more free oleic acid is formed, the acidity level rises, and flavor weakens. Extra-virgin oils keep better because they have a low acidity level to start with, but you should use lower-quality oils within months because they start out with higher acidity levels. As oil sits on your shelf, its acidity level rises daily, and soon it is not palatable. You’ll get the best quality and flavor from your olive oil if you use it within a year of pressing. Olive oil remains at its peak for about two or three months after pressing.
While in Italy in 2008, we visited the “PIG Farm” in Tuscany. A farmer and his family that has olive trees and grape vines to make local Olive oil and wine
Sources:
https://recipes.howstuffworks.com/how-olive-oil-works2.htm
https://www.americastestkitchen.com/articles/499-everything-you-need-to-know-about-olive-oil