Affirmative Action
Affirmative action is the policy of favoring members of a disadvantaged group who suffer or have suffered from discrimination within a culture. Often, these people are disadvantaged for historical reasons, such as oppression or slavery. Historically and internationally, support for affirmative action has sought to achieve goals such as bridging inequalities in employment and pay, increasing access to education, promoting diversity, and redressing apparent past wrongs, harms, or hindrances. The nature of affirmative action policies varies from region to region. Some countries, such as India, use a quota system, whereby a certain percentage of government jobs, political positions, and school vacancies must be reserved for members of a certain group. In some other regions where quotas are not used, minority group members are given preference or special consideration in selection processes.
Source & more information

Affirmative action is sometimes known as
Reservation in India and Nepal
Positive discrimination in the UK
Employment equity in Canada and South Africa(in a narrower context)