Reservation, in the context of social and political systems, refers to a policy or practice of setting aside a certain percentage or number of seats, positions, or opportunities for specific groups or categories of individuals who are typically underrepresented, disadvantaged, or historically marginalized. The aim of reservation policies is to address historical injustices, promote social equity, and ensure representation and access to resources for these groups. Reservation policies are often implemented in areas such as education, employment, and political representation. Here are some common types of reservations:

1. **Educational Reservations:** In many countries, including India, there are reservations in educational institutions, both at the primary and higher education levels. These reservations can include seats reserved for specific castes or communities to promote access to education for historically disadvantaged groups.

2. **Employment Reservations:** Some countries have employment reservations, where a certain percentage of government jobs or positions in public and private enterprises are reserved for underrepresented groups. These policies aim to provide employment opportunities and reduce economic disparities.

3. **Political Reservations:** Political reservations involve setting aside seats or constituencies in legislative bodies for specific groups, often based on ethnicity, gender, or other criteria. This ensures that these groups have a voice in the political decision-making process.

4. **Tribal Reservations:** In countries with indigenous or tribal populations, there may be reservations for these groups to protect their rights, land, and culture.

5. **Women's Reservations:** Gender-based reservations are implemented in some countries to increase the representation of women in political bodies, ensuring gender equality and addressing historical gender imbalances.

6. **Disability Reservations:** Inclusive policies may include reservations for individuals with disabilities to ensure they have access to education, employment, and other opportunities.

The specific criteria and extent of reservations vary from one country to another, as well as within different regions and states. Reservations can be a contentious issue, with debates about the appropriate balance between promoting social equity and avoiding potential discrimination against other groups. Supporters argue that reservations are necessary to rectify historical injustices and promote equality, while critics may raise concerns about reverse discrimination or the need for merit-based selection.

Reservation policies are typically subject to legal and constitutional frameworks, and their effectiveness and impact on society are topics of ongoing discussion and research.