Olive oil is made from the crushing and subsequent pressing of olives.
The fact that olives are rich in oil is reflected in the botanical name
of the olive tree-Olea europaea-as oleas means oil in Latin. Extra virgin
olive oil is derived from the first pressing of the olives and has the
most delicate flavor and most antioxidant benefits.
Pure, extra virgin olive oil is not only a light and delicate addition
to many wonderful dishes, it is one of the most health-promoting types
of oils available. Olive oil is rich in monounsaturated fat, a type of
fat that researchers are discovering has excellent health benefits.
Source: http://www.whfoods.org/genpage.php?tname=foodspice&dbid=132