You use it in your cooking all the time. It's dressing on your salad. It's tasty eaten with bread. But do you know how olive oil is produced and what all the different labels mean?

Here's some knowledge to help you be a better-informed consumer.

Harvest Time

Olive oil is the fat obtained from uncured olives, plain and simple.

Oil percentages in olives increase with ripeness. Oils made from riper fruit will be golden and less bitter, while those made from less ripe fruits are greener, peppery and more bitter and pungent.

The age of olive trees is a factor in production -- trees younger than 20 years old will produce far less fruit than those between 30 and 100 years old.

Processing Oil

After harvesting, olives must be processed quickly, before fermentation occurs.

Olives will first be laid out and sorted by age, which determines the final oils' acidity levels.

They are then washed, drained and crushed into a smooth paste -- pits and all. Heat generated during the crushing process helps the oil to flow.

The olive paste is then spread out onto fiber disks or sheets, which are stacked and placed onto a press. Or, the paste can be placed in centrifuges to separate the oil from the pulp. At this stage, the oil is a cloudy mixture that can then be decanted manually or placed into another centrifuge.

Finally, the oil will be stored as "virgin" olive oil.

Deciphering Labels

Labels on olive oils vary widely. According to Zester Daily, only one in four consumers understands olive oil grading.

Labels ultimately point to different levels of acidity, which influence how an oil tastes:

Virgin olive oil means the oil was obtained through the process described above.

Extra virgin olive oils have lower acidities between 0.2-1 percent. Cold-extraction labels on extra virgin oils mean that the maximum temperature reached during extraction was 77 degrees Fahrenheit. Higher temperatures can cause olives to lose texture, taste and aroma. The less processed an oil is the more nutrients and health benefits it will have retained. Thus, extra virgin is given the highest grade.

Pure olive oil sounds great but actually consists of refined olive oil; it has been processed and only contains small additions of virgin oil for taste. Flavor has been chemically controlled in order to mask a lesser quality oil.

Remember these simple tips when buying olive oil:

• Know where the olive oil comes from. Oils that have traveled long distances may not be fresh.
• Look for the harvest date. Unlike wine, olive oil does not improve with age and should be used and enjoyed relatively soon.
• Smell and taste it once you get it home. If it smells or tastes burnt, flat or musty, return it to the store.
• Favor domestic olive oils, such as those made in California. Olive oils made in America not only have traveled shorter distances and, as a result, retained more freshness, they consistently score high on quality amongst tasters.

More:Â In the next couple days, we'll post a guide for taste-testing olive oils. Stay tuned!