Olive groves line the rocky hillsides of the Mediterranean coast, of old in Italy and Greece they later spread to Spain and Southern France and all around the Middle East. The cultivation olive trees is quite old, at least over 4500years. The olive trees grow between 300 and 600 years old -and some really show thier age- without getting really tall. They are mature after about 20 years (first usable fruits). In the old days the olives were hand plucked or struck out of the tree using long poles while catching the falling fruits on sheets of cloth spread out under the trees (a bit like apples were harvested). Of course these days a lot of the harvesting in done (semi-) automaticaly. Also the pruning has evolved over time. Still, Odysseus would still recognise the threes.
Today olives are grown in other places as well (Hello California) though it's spreading has been slow because an olive grove is a really long term investment (and we all know how eager people are to invest in long term projects these days).
The best way to store olives is putting them in an air tight container with olive oil. Olives can be eaten fresh, directly from the tree or from a container, they are often used that way for petizers.
Most olives are sold in glass jars, with oil. Often with some red pepers added to them. Also common are olives without stone, sometimes the stones are replaced by almonds.
Olive oils come in various grades and qualities.
For the highest quality oil the best olives, usually hand-picked, are pressed quickly -- within 24 to 48 hours of harvesting for best results. The first pressing happens between great rollers of stone. Often steel rolls and presses are used these days, stone is better though because it is softer than steel and it doesn't conduct heat. The first oil produced is usually called "extra-virgin olive oil". Often "cold-pressed" is added too.
The pulp left over is then mixed with hot water and pressed again. The wesulting oil is skimmed off to make second and third press-oils.
The labeling of olive oil is quite strictly regulated, and based on the oleic acid content (R1). the lower the content the better the oil, if there is more than 4%vol the oil is not fit for consumption (bust still usable for lamps or in soap and cosmetics etc.)
Because the oleic acid can be removed chemically the labeling does no longer coincide with the production method. So if you want the best oil you should look for extra-virging and see wheter you can find "cold-pressing" or "first pressing" or dome such on the bottle.
While price is often no good indication on quality with olive oil the real first-pressed oils are the usually more expensive.
Still, as with most food stuff it's advised to try various brands and versions and select the one that tastes best. I have different brands, one for using warm (baking) and one for using cold (salad dressing, mayonaises etc.). A good test for oil is putting the bottle in the fridge (at tempeartures below 4°C) if it turns opaque and colludes, (as if there is butter mixed in) then you can be sure it's not a cold pressing. Mind you though, even the best, most pure and virgin oil will collude a bit, so you best compare different oils. And note that this doesn't mean it's a bad oil. Second and even third or warm pressings aren't bad.
Good oil can be drunk pure without leaving a raspy, acid after taste (but don't drink a whole bottle ).
And don't wory if you get a bottle of bad/old oil, it's ideal for getting your barbequeue going. ^_^
Olive oil is mostly sold in small (0.5 to 2l) glass or plastic bottles (but don't expect a first-pressing in a plastic bottle). In southern Europe and the middle east it's often sold in metal cans ranging from 1 up to 10 liters. Unless you use lots of oil you should stay away from the big cans and bottles. Like most foods the oil reacts with oxigen so look for a bottle that can be closed and that you consume in less than 2 months.
The slippery kitchen gold.