Pickled olives are either black or green, depending whether they have been harvested unripe or ripe. Pickled olives are a common decoration for cold dishes and tasty sauces. Of course, they fit best to specialities from the Mediterranean. Olive's flavour can be enhanced by preparing a paste of finely cut and squeezed olives with good olive oil. The use of olives for warm dishes is more or less restricted to Mediterranean cuisines.
Some oils are subtle and flowery, others intense and fruity.
It is probably a good idea to stock a few different varieties in the kitchen. Oils from second pressing is less aromatic, but better suited for frying. If you want to fry in extra vergine olive oil, the smoke point is raised by mixing the oil with butter, which might improve flavour anyway. Many of the dishes of Southern Europe, Western Asia and Northern Africa owe much of their character to extra vergine olive oil. Another trick is to sprinkle high-quality olive oil over fried vegetables and fish before serving.