There are many activities that are undertaken by directly using natural resources. When we produce goods by exploiting natural resources, it is an activity of the primary sector.
The secondary sectors covers activity in which the natural products are changed into other forms through ways of manufacturing that we associate with industrial activity. It is the next step after primary. For example, by using sugarcane as a raw material, we make sugar or gur.
The third category of activities falls under tertiary sector. These activities help in the development of the primary and secondary sectors. These activities, by themselves, do not produce goods but they are an aid or a support for the production process, for example, transport, communication, etc.
Thus, we can clearly say that the three sectors of economy are highly interdependent.