Middle Class: Individuals who fall between the working-class and upper class socio-economic groups. They typically have stable employment, moderate incomes, own homes, and enjoy some degree of financial security.
Labor Unions: Organizations formed by workers to protect their rights and negotiate collectively with employers for better wages, benefits, working conditions, etc.
Income Inequality: The unequal distribution of income among different individuals or groups within society. It is often measured by the Gini coefficient.