Factors such as topography, climate and natural resources play a crucial role in determining where people choose to settle. The physical environment has a significant impact on the location and growth of human settlements. For example, flat areas are often preferred for settlements, as they are easier to build, while mountainous regions are more difficult to inhabit. Areas with fertile soil, access to water, and a temperate climate are more likely to attract settlement than arid, arid, or areas prone to natural disasters. Landscape history studies the shape (morphology) of settlements, for example, if they are dispersed or nucleated.
Therefore, urban morphology can be considered a special type of historical and cultural studies of the landscape. Settlements can be ordered by size, centrality, or other factors to define a hierarchy of settlements. A hierarchy of settlements can be used to classify settlements around the world, although a settlement called a city in one country can be a town in other countries; or a large city in some countries can be a city in others.