Heavy industry is an industry that involves one or more characteristics such as large and heavy products; large and heavy equipment and facilities (such as heavy equipment, large machine tools, huge buildings and large-scale infrastructure); or complex or numerous processes. Because of those factors, heavy industry involves higher capital intensity than light industry does, and it is also often more heavily cyclical in investment and employment.
Transportation and construction along with their upstream manufacturing supply businesses have been the bulk of heavy industry throughout the industrial age, along with some capital-intensive manufacturing. Traditional examples from the mid-19th century through the early 20th included steelmaking, artillery production, locomotive erection, machine tool building, and the heavier types of mining. From the late 19th century through the mid-20th, as the chemical industry and electrical industry developed, they involved components of both heavy industry and light industry, which was soon also true for the automotive industry and the aircraft industry. Modern shipbuilding (since steel replaced wood) is considered heavy industry. Large systems are often characteristic of heavy industry such as the construction of skyscrapers and large dams during the post-World War II era, and the manufacture/deployment of large rockets and giant wind turbines through the 21st century.
Many East Asian countries rely on heavy industry as key parts of their overall economies. This reliance on heavy industry is typically a matter of government economic policy. Among Japanese and Korean firms with "heavy industry" in their names, many are also manufacturers of aerospace products and defense contractors to their respective countries' governments such as Japan's Fuji Heavy Industries and Korea's Hyundai Rotem, a joint project of Hyundai Heavy Industries and Daewoo Heavy Industries.
In 20th-century communist states, the planning of the economy often focused on heavy industry as an area for large investments, even to the extent of painful opportunity costs on the production-possibility frontier (classically, "lots of guns and not enough butter"). This was motivated by fears of failing to maintain military parity with foreign capitalist powers. For example, the Soviet Union's manic industrialization in the 1930s, with heavy industry as the favored emphasis, sought to bring its ability to produce trucks, tanks, artillery, aircraft, and warships up to a level that would make the country a great power. China under Mao Zedong pursued a similar strategy, eventually culminating in the Great Leap Forward of 1958-1960, an attempt to rapidly industrialize and collectivize. This industrialization attempt failed to create industrialization and instead caused the Great Chinese Famine, in which 25-30 million people died prematurely.
Heavy industry is also sometimes a special designation in local zoning laws. This allows industries with heavy impacts (on environment, infrastructure, and employment) to be sited with forethought. For example, the zoning restrictions for landfills usually take into account the heavy truck traffic that will exert expensive wear on the roads leading to the landfill.