"Olive oil" is not one product - it is a ladder of grades defined by how the oil is extracted and how much free acidity it carries. Understanding the ladder is the difference between over-paying for extra virgin where a refined oil would do, and under-specifying where flavour actually matters.
The virgin grades (mechanical extraction)
Virgin oils are pressed from olives by mechanical means only - no solvents, no refining.
- Extra virgin (EVOO) - free acidity ≤ 0.8%, no sensory defects. The top grade: fruity, aromatic, often peppery. Used where the oil is tasted.
- Virgin - free acidity ≤ 2.0%, minor defects allowed. A step down in flavour and price.
- Lampante - above 2.0% or defective; not fit for consumption as-is and must be refined.
The refined grades
Oils that do not meet virgin standards are refined - stripped of colour, aroma and free fatty acids - to make them usable.
- Refined olive oil - free acidity ≤ 0.3%, neutral and light, with a higher smoke point.
- "Olive oil" (formerly "pure") - a blend of refined olive oil with some virgin oil to add back a little flavour and colour.
The pomace grades
After pressing, oil still remains in the pomace (the pulp and pits). It is solvent-extracted and refined.
- Refined olive-pomace oil - free acidity ≤ 0.3%.
- Olive-pomace oil - the refined pomace oil blended with a little virgin oil; free acidity ≤ 1.0%. The most economical olive-derived oil, with a high smoke point.
Choosing by use
As a rule: if the oil is tasted, buy extra virgin. If you want an olive-oil base without strong flavour, buy refined or an "olive oil" blend. If cost and heat stability dominate - high-volume frying - olive-pomace oil is usually the right call. The grade you specify should follow the job, not the label.