In business, an industry generally involves the production or manufacture of products or goods from raw materials. Industries generally deal with only one or a small range of products. However there may be many businesses within an industry sector, either concentrating on an individual product or raw material, a particular stage in the industrial process, or a particular geographic location. These businesses often come together in co-operative industrial associations in order to address challenges and problems faced jointly by all the individual businesses in a particular industry.

Businesses or individual enterprises are often classified by their industry. While industries are often classified into three sectors, the classification is not strict and some industries may cross sectors:

• The Primary Sector of industry generally involves the conversion of natural resources into primary products. Most products from this sector are considered commodities or raw materials for other industries. Major businesses in this sector include Agriculture, Fishing and Forestry as well as Mining for minerals. Downstream manufacturing industries that aggregate, pack, package, purify or process the raw materials close to the primary producers are normally considered part of this sector, especially if the raw material is unsuitable for sale or difficult to transport long distances.
• The Secondary Sector of industry generally takes the output of the primary sector and manufactures finished goods or products to a point where they are suitable for use by other businesses, for export, or sale to domestic consumers. This sector is often divided into light industry and heavy industry. These industries often consume large quantities of energy and require factories and machinery to convert the raw materials into goods and products. They also produce waste materials and waste heat that may pose environmental problems and/or cause pollution.
• The Tertiary Sector of industry is also known as the service industry. It involves the provision of services to other businesses or people. Services may involve the transport, distribution and sale of goods from producer to a consumer as may happen in wholesaling and retailing, or may involve the provision of a service, such as in tourism or entertainment. The goods may be transformed in the process of providing the service, as happens in the restaurant industry, however the focus is on people interacting with people and serving the customer rather than transforming goods.