The Olive was native to Asia Minor and spread from Iran, Syria and Palestine to the rest of the Mediterranean basin 6,000 years ago.  It is among the oldest known cultivated trees in the world - being grown before the written language was invented.   It was being grown on Crete by 3,000 BC and may have been the source of the wealth of the Minoan kingdom.  The Phoenicians spread the olive to the Mediterranean shores of Africa and Southern Europe. Olives have been found in Egyptian tombs from 2000 years BC. 

The olive culture was spread to the early Greeks then Romans.  As the Romans extended their domain they brought the olive with them. In the past several hundred years the olive has spread to North and South America, Japan, New Zealand and Australia.

Source: www.oliveoilsource.com

Types of olive oil

Generally, olive oil is extracted by pressing or crushing olives. Olive oil comes in different varieties, depending on the amount of processing involved. Varieties include:

Extra Virgin - considered the best, least processed, comprising the oil from the first pressing of the olives.
Virgin - from the second pressing.
Pure - undergoes some processing, such as filtering and refining.
Extra Light - undergoes considerable processing and only retains a very mild olive flavour.

When buying olive oil you will want to obtain a high quality EXTRA VIRGIN oil. The oil that comes from the first "pressing" of the olive, is extracted without using heat (a cold press) or chemicals, and has no "off" flavors is awarded "extra virgin" status. The less the olive oil is handled, the closer to its natural state, the better the oil. If the olive oil meets all the criteria, it can be designated as "extra virgin".

What is pure and light olive oil? "Pure" olive oil is made by adding a little extra virgin olive oil to refined olive oil. It is a lesser grade oil that is also labeled as just "olive oil" in the U.S.

"Light" olive oil is a marketing concept and not a classification of olive oil grades. It is completely unregulated by any certification organizations and therefore has no real precedent to what its content should be. Sometimes, the olive oil is cut with other vegetable oils.

Source: healingdaily.com