Geographical segregation exists whenever the proportions of population rates of two or more populations are not homogenous throughout a defined space. Populations can be considered any plant or animal species, human genders, followers of a certain religion, people of different nationalities, ethnic groups, etc.
In social geography segregation of ethnic groups, social classes and genders is often measured by the calculation of indices such as the index of dissimilarity. Different dimensions of segregation (or its contrary) are recognised: exposure, evenness, clustering, concentration, centralisation, etc. More recent studies also highlight new local indices of segregation.
Human geographical segregation
Segregation, as a broad concept, has appeared in all parts of the world where people exist—in different contexts and times it takes on different forms, shaped by the physical and human environments. The spatial concentration of population groups is not a new phenomenon. Since societies began to form there have been segregated inhabitants. Either segregated purposefully by force, or gradually over time, segregation was based on socio-economic, religious, educational, linguistic or ethnic grounds. Some groups choose to be segregated to strengthen social identity.