How do industries help to strengthen the economy of a country?

Industries help to strengthen the economy of a country in the following ways:
(i) Industries help in the establishment of the infrastructure of the country such as dams, railways, etc. Infrastructural development helps in the growth of other sectors also.
(ii) Industries help in improving the agricultural sector with mechanised means of production such as tractors, threshers, etc and also with fertilisers, insecticides. etc.
(iii) Expansion of capital goods industries pave the way for industrial growth and as a result, the economy is able to undertake large scale production of goods at low cost.
(iv) Industrialisation helps a country to become self-reliant in the production of defense goods.