An industry is a sector that produces goods or related services within an economy. The major source of revenue of a group or company is an indicator of what industry it should be classified in. When a large corporate group has multiple sources of revenue generation, it is considered to be working in different industries. The manufacturing industry became a key sector of production and labour in European and North American countries during the Industrial Revolution, upsetting previous mercantile and feudal economies. This came through many successive rapid advances in technology, such as the development of steam power and the production of steel and coal.
Following the Industrial Revolution, possibly a third of the economic output came from manufacturing industries. Many developed countries and many developing/semi-developed countries depend significantly on manufacturing industry.