What are some examples of complex institutions in today's civilization?

Examples of complex institutions are government, economy, tax systems and law. These types of institutions are used to stabilize the civilization so it won't fall.

The Social structure was cut into five different parts. The Pharaoh is on the top by himself. Government Officials, Nobles, and Priests were next. Then it droped down to traders, artisans, and scribes: Tis is present day middle class. The next type of people were the farmers and herders, they were considered poor. Then at the bottom are the slaves and unskilled workers.