Affirmative action or positive discrimination is a set of government policies aimed to advance discriminated minorities and to help them achieve equality with mainstream citizens. Traditionally, these policies are used in countries burdened by a past of slavery, discrimination, racism, ethnic cleansing etc.
From the viewpoint of human rights, these policies are superfluous because rights already demand equality and non-discrimination. Correctly applying human rights standards is therefore sufficient protection for all minorities.
However, this is only true in ideal situations. The burden of the past, or unwillingness by some to correctly apply those human rights standards necessary for equality and non-discrimination, may require some temporary measures, on top of human rights, in order to undo discrimination and inequality. But these measures should be chosen with restraint, because they imply reverse discrimination of other citizens.