23 of the 24 countries of the world that are the major producers of olive oil belong to a non-governmental regulating body called the International Olive Oil Council. The 24th country has antiquated laws and regulations about olive oil and has not signed on to the Council. In 23 of those countries, an olive oil sold as "Extra Virgin" meets quite a stringent set of rules that dictate what's being sold to you is good, quality olive juice... not the cooking oil that refined olive oil is, barely tasting separate from its crude colleagues, canola oil, vegetable oil, corn oil; "Extra Virgin Olive Oil" is more on par with hazelnut oil, pinenut oil, almond oil, but really a league above them as well. Olive Oil has more variations of taste than butter--and butter tastes damn good. The highest quality olive oils have as much variation as the highest quality honeys, or the variations in cheese. They are beautiful expressions of the diversity of the olive and its connection to the land on which it grows.
The 24th country is the United States, which, save for a ribald band of olive oil producers in California that have formed the California Olive Oil Council, has no meaningful regulations on what can be called "Extra Virgin" olive oil. The minimal requirements set by U.S. laws allow the most indistinct, bland, and flavorless oils to still call themselves "Extra Virgin." It's meaning as a label has been severely diminished. So,
FACT #1 - "Extra Virgin" on a label of an olive oil bottle means absolutely nothing in regard to the taste of the oil in that bottle.
Once the physical means of extracting olive juice have been exhausted, the resulting oil is stored in huge stainless steel vats. Many olive oils are labeled "best used by" with a date stamped two years after the bottling date. That's the minimal requirements if an olive oil producer puts a "best used by" on their bottle. But here's the catch for the consumer: olive oil starts degrading the moment it's crushed out of that olive--it no longer has nature to protect it and in about two years, give or take quite a few months, that oil will go rancid. It's degrading while it's in that stainless steel vat. We can slow it down, but not WAY down--not without using chemistry and high temperatures to remove all impurities from the oil. It's that purity that U.S. laws regulate (and don't get me started on the fact that these are self-regulating laws, with no meaningful inspections)--which means that U.S. laws don't help people recognize fresh, tasty olive juice.
FACT #2 - "Best Used By" means absolutely nothing if not accompanied by a "Harvested In" date as well. The average time one has to use a high-quality extra virgin olive oil is about two years, some varieties giving nearly three years or even more, other varieties giving only a year.
FACT #3 - Not all "extra virgin" olive oils are as high quality as others, even when following the rules of the I.O.O.C. Look for the initials A.O.C. or D.O.P. (sometimes D.P.O.) as the easiest sign to see of a high-quality olive oil.