Basic industries supply their products as raw materials to other industries. This industry produces iron and steel, which is used for manufacturing machines, tools and equipments. Machineries and tools are basic for any manufacturing process.
It also provides raw materials for heavy engineering automobiles, shipbuilding, manufacturing of locomotives, etc.
The development of these heavy industries is dependent on the supply of iron and steel. Thus, iron and steel industry plays a key role in the development of any manufacturing industry. Iron and steel is a heavy industry because all the raw materials (iron ore and limestone are examples) are heavy and bulky. They involve heavy transportation cost. Besides, the finished goods are generally either heavy or bulky or both.
Thus, it can be concluded that Iron and steel industry is basic as well as heavy industry.