Classical economic theory, associated with economists like Adam Smith and David Ricardo, posits that income inequality arises from differences in individual productivity and contributions to the economy.

The Kuznets curve hypothesizes that income inequality tends to rise in the early stages of economic development and then decline as countries reach higher levels of development.

The Industrial Revolution, which began in the late 18th century, brought about significant technological and economic changes that contributed to the rise of economic inequality.

Relative deprivation in economic inequality focuses on individuals' subjective perceptions of inequality based on comparisons with others, rather than objective measures of income or wealth.

Marxian economic theory, developed by Karl Marx, emphasizes the role of class relations and the exploitation of labor in creating and perpetuating economic inequality.

The Gini coefficient is a widely used measure of income inequality, ranging from 0 (perfect equality) to 1 (perfect inequality).

The '1%' refers to the top 1% of income earners in a society, often used to highlight the concentration of wealth and income among a small group of individuals.

The Reagan Era, referring to the presidency of Ronald Reagan in the 1980s, is often associated with policies that contributed to a widening of the income gap in the United States.

Trickle-down economics is a theory that suggests that economic benefits from tax cuts and other policies favoring the wealthy will eventually trickle down to the poor and benefit the entire economy.

Occupational segregation refers to the concentration of certain occupations among specific demographic groups, such as gender, race, or ethnicity, leading to disparities in income and opportunities.

Institutional economic theory focuses on the role of institutions, such as property rights, legal systems, and social norms, in shaping economic outcomes and inequality.

Intergenerational mobility refers to the extent to which individuals' economic status is correlated with the economic status of their parents or ancestors.

Human capital refers to the skills, knowledge, and abilities of individuals that contribute to their productivity and earning potential, such as education, training, and experience.

The New Deal Era, referring to the presidency of Franklin D. Roosevelt in the 1930s, is often associated with policies that helped reduce economic inequality during the Great Depression.

Economic mobility refers to the extent to which individuals' economic status can change over time, either upward or downward.