Royal Dutch Shell is an independent oil and gas company. The Company owns, directly or indirectly, investments in the numerous companies constituting Shell. Shell is engaged worldwide in the principal aspects of the oil and gas industry and also has interests in chemicals and other energy-related businesses. The Company 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 that is converted into synthetic crude oil, and wind energy. Downstream is engaged in manufacturing; distribution and marketing activities for oil products and chemicals. Corporate represents the key support functions, comprising holdings and treasury, headquarters, central functions and Shell's self-insurance activities.