This document discusses key aspects of cities and urban settlements. It begins by noting that while definitions of cities vary, some common characteristics are a large population, tall buildings close together, and economic activities focused on secondary and tertiary sectors like industry and services. Rural settlements, in contrast, have lower populations and focus on primary sectors like agriculture. The document then examines common functions of cities like residential, commercial, industrial, and political uses. It also explores urban morphology and the different patterns cities can take, like grids, radial plans, and irregular forms. Finally, the internal structure of cities is discussed, differentiating city centers, peri-urban areas on the outskirts, and further outskirts where newer development is located.