Royal Dutch Shell plc (Shell) is an independent oil and gas company, based in the United Kingdom. It operates in three segments: Upstream, Downstream and Corporate. Upstream combines the operating segments Upstream International and Upstream Americas, which are engaged in searching for and recovering crude oil and natural gas, the liquefaction and transportation of gas, the extraction of bitumen from oil sands and converting it into synthetic crude oil, and wind energy. Downstream segment is engaged in manufacturing, distribution and marketing activities for oil products and chemicals, alternative energy (excluding wind), and carbon dioxide (CO2) management. Corporate segment represents the key support functions, such as Shell's holdings, treasury and self-insurance organization. The Company operates through numerous subsidiaries in Europe, Asia, Oceania, Africa and North America.