The basic needs of humankind are food, clothing and shelter. For food, humans cultivate several different crops and produce food. The cultivation of crop is generally referred to as agriculture. Humans process these agricultural products through flour mills and preserving industries into palatable food products. The industries involved here are food processing industries. For clothing, humans produce cotton, jute, silk and wool and manufacture clothing in the factories. This is called textile industry. They also manufacture building materials such as bricks, iron and steel products, cement and the like. Therefore, we may define 'industry' as that activity which produces what human beings need in their lives and living.
When humans were primitive, their needs were but a few. Industry was not extensive. With modernisation, the necessities were increasing. With population increases, consumption was on the rise. Humans could not meet their needs only by manual production. Hence, the need to discover machines arose. With the industrial changes in the eighteenth century, industrial activities grew rapidly. As a consequence, humans have developed a multitude of industries to satisfy their needs.
The industries so developed until now could be classified as the four following industries, on the basis of their state of production:
1. Primary industries.
2. Secondary industries.
3. Tertiary industries.
4. Quaternary industries.
The industries that help extract resources directly from nature are collectively called 'primary industries'. These are fundamental to other allied industries. Hunting, fishing, cultivation of crops and mining are 'the primary industries'. It is the primary industries that provide the food the humans need. They also provide for the raw materials the secondary industries demand.
Industries which transform natural resources into products that humans could consume are called 'the secondary industries'. For instance, cotton from agriculture is transformed into clothing in these industries. Likewise, resources obtained from mining industries are converted into products that humans need.
The products of the primary and secondary industries reach the people in different parts of the world through transport, trade and allied institutions such as banks, telecommunications, recreation and tourism and such are then called 'the tertiary industries'
These are industrial activities that help the activities under the earlier three sectors. These are called 'the quaternary industries'. These include education, research, administration, financial management, legal activities and medicine besides several others. The activities of
this group of industries are not linked to commodities and products, rather these are linked to people. In these, high quality skills and training are especially needed.
All products that we consume are produced and provided by the four industries above. For example, the raw materials needed to manufacture bicycles that we use for transport are from the four industries: iron ore and sandstones that form the basis for glass come from mining industries and rubber comes from plantations. These are then transformed into steel pipes and glasses and tyres and tubes by the secondary industries. Bicyles are then manufactured to be sold in the market. It is in the sale of these bicycles that the tertiary industries are important. For performing activities related to the refinement, promotion and sale are aided by the quaternary industries. In fact, all consumer products that we consume are produced with the help of all the four industries.