When we produce a good by exploiting natural resources, it is an activity of the primary sector. It forms the base for all other products that we subsequently make. Since most of the natural products we get are from agriculture,dairy,fishing,forestry; this sector is also called agriculture and related sector.
The secondary sector covers activities in which natural products are changed into other forms through ways of manufacturing that we associate with industrial industrial activity.Since this sector is associated with the different kinds of industries, it is also called as industrial sector.
Tertiary sector generate services rather than goods which supports the development of primary and secondary sectors like banking, communication,transport,trade etc. It is also known as the service sector.

Primary sector provides raw material to the secondary or industrial sector while tertiary sector transports the product to the final consumer!!