The Royal Dutch Shell plc explores for crude oil and natural gas around the world, both in conventional fields and from sources, such as tight rock, shale and coal formations. The Company's segments include Integrated Gas, Upstream, Downstream and Corporate. The Integrated Gas segment is engaged in the liquefaction and transportation of gas and the conversion of natural gas to liquids to provide fuels and other products, as well as projects with an integrated activity, ranging from producing to commercializing gas. The Upstream segment includes the operations of Upstream, which is engaged in the exploration for and extraction of crude oil, natural gas and natural gas liquids, and the marketing and transportation of oil and gas, and Oil Sands, which is engaged in the extraction of bitumen from mined oil sands and conversion into synthetic crude oil. The Downstream segment is engaged in oil products and chemicals manufacturing, and marketing activities. The Corporate segment comprises holdings and treasury, self-insurance activities, and headquarters and central functions of the company.