Social inequality occurs when resources in a given society are distributed unevenly, typically through norms of allocation, that engender specific patterns along lines of socially defined categories of persons. Economic inequality, usually described on the basis of the unequal distribution of income or wealth, is a frequently studied type of social inequality. Though the disciplines of economics and sociology generally use different theoretical approaches to examine and explain economic inequality, both fields are actively involved in researching this inequality. However, social and natural resources other than purely economic resources are also unevenly distributed in most societies and may contribute to social status. Norms of allocation can also affect the distribution of rights and privileges, social power, access to public goods such as education or the judicial system, adequate housing, transportation, credit and financial services such as banking and other social goods and services. While many societies worldwide hold that their resources are distributed on the basis of merit, research shows that the distribution of resources often follows delineations that distinguish different social categories of persons on the basis of other socially defined characteristics. For example, social inequality is linked to racial inequality, gender inequality, and ethnic inequality as well as other status characteristics.