In macroeconomics, an industry is a branch of an economy that produces a closely related set of raw materials, goods, or services. For example, one might refer to the wood industry or the insurance industry. For a single group or company, its dominant source of revenue is typically used to classify it within a specific industry. However, a single business need not belong to one industry, such as when a large business is diversified across separate industries (often referred to as a conglomerate). Economic theories group industries further into economic sectors.