Nature

Olive oil

Probably the most widely-used oil in cooking, olive oil is pressed from fresh olives. It's mainly made in the Mediterranean, primarily in Italy, Spain and Greece (though countries such as America and Australia also produce it). Much like wine-making, climate, soil and the way the olives are harvested and pressed all have an impact on an oil's character.

Olive oil is assessed on three criteria - fruitiness, bitterness and pepperiness - the flavour, smell and colour can vary radically, both according to its origin, as well as whether it's extra virgin (the finest grade) or not.

Generally speaking, the hotter the country, the more robust the flavour of the oil. It is also possible to flavour olive oil with herbs and spices by steeping them in the oil for ten days or so (though chilli needs far less time).