Extra Virgin and Protected

• The purest-tasting oils have been minimally processed to keep their flavor and aroma molecules intact, so look for "extra virgin" on the label. Those labeled "pure olive oil" or "olive oil" are usually made with lower-quality oils that have undergone a lot of manipulation. The oil you buy should also come in a dark container; this means it's protected from light, which degrades the oil's quality. While the term "refined" on the bottle may make the oil sound high-quality, it actually means it has been processed and may not taste good on your salad.

The Date Is Important

• Unlike wine, olive oil does not improve with age. Younger oils retain more flavor, which is important when you dress a salad. Look for an oil with a harvest date close to your purchase date. If your bottle doesn't list the harvest date, at least pay attention to the "best by" date. Avoid those that expire soon -- you'll know they are not optimally fresh.

Flavor

• The best olive oils are described as tasting "peppery," "fruity" and "grassy." While these terms sometimes turn consumers off, they are positives -- especially when you want a flavorful oil for a salad. When it comes down to it, though, you have to find an oil that tastes good to you. Your best bet is to go to a specialty store where they offer tastings of the products, so you can decide what flavors meld with your palate. When you use the oil as a primary component in a salad dressing, its flavor will stand out. Bland or rancid-tasting oils are a definite no-no.

Point of Origin

• Although Italian olive oils have a good reputation, an Italian heritage doesn't guarantee the olive oil will be good for your salad. Spain, California and Greece are other great producers of olive oil. Eataly restaurant olive-oil specialist Nicholas Coleman, interviewed in "Real Simple," suggests looking for an estate name on the bottle, often an indication of quality since producers don't put the estate name on products of which they aren't proud. You can also look for special designations, such as PDO, which stands for the European Union's official Protected Designation of Origin, or, for American varieties, the U.S. Department of Agriculture's organic seal.