There's a lot you can learn about an olive oil by looking at its label. More expensive oils tend to offer the most information:
"100% EXTRA VIRGIN OLIVE OIL"
Extra-virgin olive oil has nothing to do with purity. The term refers to oils with an acidity level of less than 1 percent. Virgin olive oil is the term used for oils with an acid level of 1 to 3 percent. The words extra virgin are also meant to denote a fine, fruity character.
This refers to the process of producing the oil. When olives are cold-pressed, they are first washed, then literally pressed between stone rollers to release the oil. No mechanical devices or chemicals should be used in the cold-press method, but the process is unregulated.
"CULTIVATED, PRESSED AND PACKAGED IN ITALY" The entire process used to make this oil took place in Italy. Some oils are sent from the country where the olives are grown to another country to be labeled and packaged. Then, for example, if the oils are packaged in Italy, the bottle can say "Made in Italy."
"USDA AND ITALIAN ORGANIC SEALS" The U.S. Department of Agriculture seal on the right of the bottom of the label means that at least 95 percent of the content is organic. The Italian seal -- next to the USDA seal -- designates a product that has been certified 100 percent organic by the Agency for the Control of Organic Products in Italy.
"3/5/06" (on the nutritional label on the back of the bottle): Olive oils deteriorate over time. They are at their best in the first 12 months after bottling and are fine through the next 12 months. Better olive oils often have a "sell by" date, in this case March 5, 2006.