Oil and natural gas are major industries in the energy market and play an influential role in the global economy as the world's primary fuel sources. The processes and systems involved in producing and distributing oil and gas are highly complex, capital-intensive, and require state-of-the-art technology.

This guide looks at the business of oil and gas and is intended to serve as a research aid to sources worldwide, with a specific emphasis on the United States. It covers a brief history of the oil and gas industry, an overview of companies and organizations, statistic and pricing resources, and regulations. The industry is often divided into three segments:

• upstream, the business of oil and gas exploration and production;
• midstream, transportation and storage; and
• downstream, which includes refining and marketing.

These three areas are reflected in the organization of the guide. Renewable and alternative energy companies are discussed in our Green Business: Sources of Information Guide.