1) Primary Activity - This is the extractive sector of an economy, such as mining or agriculture. It is in this activity that workers come into direct contact with the environment. It is often considered the most basic level of economic activity. 2) Secondary Activity - This is the activity that involves the manufacture of raw materials into finished industrial products. A canning factory or lumber yard are examples. 3) Tertiary Activity - This is service-based economic activity. This includes areas such as education, retail, finance, and government work. 4) Quaternary Activity - This involves the collection and manipulation of information. This is the most recent form of economic activity, and it is based on the development of technology.