A term referring to the degree to which a given company participates in all phases of the petroleum industry. An oil company is considered fully integrated, for example, when it handles its own oil from the well head to the retail gasoline pump. Such a company would be active in exploration, crude oil production, transportation, refining and marketing - all under its brand name. This is known as "vertical integration." By comparison, "horizontal integration" refers to the degree to which a company participates in diversified interests other than its principal business. In the energy field, the term applies to those companies which, in addition to oil activities, have substantial positions in coal, uranium, geothermal energy, etc.