Exxon Mobil is a multinational oil and gas corporation headquartered in Irving, Texas, US. It is the largest direct descendant of John D. Rockefeller's Standard Oil, and was formed in 1999 by the merger of Exxon and Mobil. It holds an industry-leading inventory of global oil and gas resources. It is among the world's largest refiners and marketers of petroleum products and its chemical company ranks among the world's largest. It is also a technology company, applying science and innovation to deliver energy. It comprises 10 separate companies, which make up its Upstream, Downstream and Chemical businesses.