This article aims to clarify the business activities of Exxon Mobil Corporation over a period of more than thirty years since the early 1970s. The main topics consist of upstream businesses, downstream businesses, diversification, organizational structures, and the Exxon Mobil Merger. Another purpose of this article is to review Exxon: Transforming, 1973-2005 by Joseph A. Pratt with William E. Hale, which was published in 2013 and is the fifth volume of the history of the Company. The main conclusions are the following: (1) The upstream business of the Company has already been discussed in my past articles, so this paper almost entirely foregoes a full description of this side of the company’s business. Instead, it chiefly focuses on a cri...