Discrimination based on skin tone, also known as colorism or shadeism, is a form of prejudice and discrimination in which individuals of the same race receive benefits or disadvantages based on their skin tone. More specifically, colorism is the process of discrimination which marginalizes darker-skinned people over their lighter-skinned counterparts. Historically, colorism on a global scale has colonial roots, ranging from early class hierarchies in Asia to its impact on Latinos and African Americans through European colonialism and slavery in the Americas.

Colorism focuses on how racism is expressed in the psychology of a people and how it affects their concepts of beauty, wealth, and privilege. A key difference between racism and colorism is that while racism deals with the subjugation of one group by another or the belief in racial supremacy, colorism deals with in-group discrimination in addition to between-group discrimination.

Research has uncovered extensive evidence of discrimination based on skin color in criminal justice, business, the economy, housing, health care, the media, and politics in the United States and Europe. In addition, there has been research that evidently shows biases based on skin tone in the educational system. Students of color are facing higher education costs and inequalities in advanced programs and are targeted by their teachers or peers from other marginalized groups. In addition to this issue being documented in the United States, lighter skin tones have been considered preferable in many countries in Africa, Asia, and Latin America due to internalized colorism.

Although less historically significant, prejudice within groups can also be directed toward lighter-skinned individuals, often due to the perception of albinism as a disease. This is referred to as reverse colorism.

Racism affects almost every aspect of contemporary life. Research shows that ethnic minorities are offered fewer opportunities in higher education and employment, are subject to increased scrutiny by police, and are less likely to receive adequate care from physicians.

Several meta-analyses find extensive evidence of ethnic and racial discrimination in hiring in the North American and European labor markets. A 2016 meta-analysis of 738 correspondence tests in 43 separate studies done in OECD countries in 1990–2015 finds that there is extensive racial discrimination within both the European and North American hiring processes. Equivalent minority candidates need to send around 50% more applications than majority candidates to be invited for an interview. Recent research in the U.S. shows that socioeconomic and health inequality among African Americans along the color-continuum is often similar or even larger in magnitude than what exists between whites and African Americans.

Skin-whitening treatments and colorism inside of own ethnicity is more common in West and South parts of Africa.

In some parts of Africa, people with lighter skin are thought to be more attractive and likely to find more success than those with darker skin tones. In some countries, this barrier has resulted in millions of women and men turning to skin-lightening treatments, many of which are harmful to the body.