Overcrowding happens when too many people live in a space that is too small. It can occur in homes, buildings, or entire neighborhoods. This situation is common in fast-growing cities and some refugee camps.

In crowded areas, several people may share one room or small living space. Cities such as Mumbai or Lagos have neighborhoods where housing is very dense. Overcrowding is measured by the number of people per room or area.

It is studied in urban planning using surveys, maps, and housing data. Overcrowding helps show how space and resources are used in different places.