Pressed from pitted ripe (black) olives. Olive oil is graded based on its acidity. The lower the acidity, the stronger the olive flavor. Cold-pressed (processed without heat) oil is called extra-virgin olive oil and is the result of the first pressing of the olives. For the second olive pressing, solvents are used, and this yields virgin olive oil. Successive pressings yield less-delicate oils, such as all-purpose olive oil. Use olive oil for marinades, salad dressings and cooking.