Using white skin colour as the standard, colourism is the allocation of privilege and favor to lighter skin colours and disadvantage to darker skin colours.

It is a term coined by author Alice Walker in her book In Search of our Mothers’ Gardens. Walker defined colourism as the ‘prejudicial or preferential treatment of same-race people based solely on their colour.’

Colourism is where prejudicial treatment is given to darker- skinned Black people and People of Colour and preferential treatment is given to lighter-skinned Black people and People of Colour. It operates both within and across racial and ethnic groups. .

References:

• Colorism, Racial Equity Tools Glossary, 2020. 
• Critical Race Theories, Colorism, and the Decade’s Research on Families of Color, Burton, Linda M et al., “ Journal of Marriage and Family 72 (2010), pp. 440–459.
• In search of our mothers’ gardens: Womanist prose. Alice Walker, San Diego: Harcourt Brace Jovanovich, 1944 (1983).