(i) Primary Sector (or Agriculture sector). It includes all those economic activities which are connected with extraction and production of natural resources, e.g., agriculture, fishing, mining, etc.
(ii) Secondary Sector (or Industrial sector). It includes all activities which are concerned with the processing materials which have already been extracted at the primary stage, e.g., the mining of iron ore is primary industry, but manufacture of steel is secondary industry.
(iii) Tertiary Sector (or Service sector). It is concerned with providing support services to primary and secondary sector and includes transport, banking, insurance, warehousing, communication, advertising, etc. It facilitates smooth flow of goods and services in the economy. Importance of tertiary sector has been observed in the last decade and its contribution to GDP has also risen.