Oil and gas companies extract, produce, refine, transport and/or process oil and natural gas resources, as well as related products. This vertical encompasses all sectors of the oil and gas industry, including the upstream (exploration, extraction, operation of wells), midstream (transportation of refined and unrefined goods via pipeline, oil tanker, rail, or truck), and downstream (refining and processing of crude oil, as well as purifying of raw natural gas). Texaco, for example, distributes petroleum and gasoline products through gas stations.