Affirmative action refers to a set of policies and practices within a government or organization designed to address past and present discrimination against specific groups, typically based on race, ethnicity, gender, religion, or caste. The primary goal of affirmative action is to promote equal opportunity, achieve diversity, and compensate for historical disadvantages faced by these marginalized groups.

These policies often involve preferential treatment in areas such as employment, education, scholarships, and government contracts. For instance, universities might consider an applicant's racial or ethnic background as one factor among many in admissions, or companies might set targets for hiring individuals from underrepresented groups.

The rationale behind affirmative action is multifaceted:

1. Compensatory Justice: To rectify the lingering effects of historical injustices and systemic discrimination.
2. Distributive Justice: To ensure a more equitable distribution of opportunities and resources in society.
3. Diversity: To enrich institutions and workplaces by bringing in a wider range of perspectives and experiences, which is believed to foster innovation and better decision-making.
4. Breaking Cycles of Disadvantage: To provide a boost to individuals from disadvantaged backgrounds, helping them overcome barriers that might otherwise prevent their upward mobility.

However, affirmative action remains a contentious issue. Critics often argue that it leads to 'reverse discrimination,' compromises meritocracy by favoring less qualified candidates, and can stigmatize beneficiaries. Proponents counter that it is a necessary tool to achieve substantive equality in societies still grappling with the legacies of discrimination.