What is the regime in Part 5?

Chapter 3

There are different types of regimes because there are many parts to a city. Among the city's inhabitants there are differences in wealth, trade, virtue, family and so on. The regime is simply the arrangement of offices, and different cities arrange their offices in accordance with which group in the city is preeminent. The two main types of regimes that exist are democracy and oligarchy, since people consider aristocracy to be a sort of oligarchy and "so-called" polity to be a type of democracy.