Colorism is prejudice of or discrimination against other people based on skin color. The concept is different from racism because it’s usually used to describe discrimination within a certain race or ethnic group, based on the tone of skin color, rather than discrimination of an entire race or ethnic group. In general, this means that lighter skin tones are preferred and darker skin is considered less desirable. Lighter-skinned members of a certain race or ethnic group can discriminate against members with darker tones within the same group, but colorism more often means a general social preference for lighter skins.
One cause of colorism may be a traditional and historical preference for light and an abhorrence of darkness, light being good and godly, dark being evil and scary. However, I won’t explore the causes and just limit myself to some examples. There’s the one I mentioned some time ago, and then there’s this one:
Villanova researchers studied more than 12,000 cases of African-American women imprisoned in North Carolina and found that women with lighter skin tones received more-lenient sentences and served less time than women with darker skin tones. The researchers found that light-skinned women were sentenced to approximately 12 percent less time behind bars than their darker-skinned counterparts. Women with light skin also served 11 percent less time than darker women.
The study took into account the type of crimes the women committed and each woman’s criminal history to generate apples-to-apples comparisons. The work builds on previous studies by Stanford University, the University of Colorado at Boulder and other institutions, which have examined how “black-looking” features and skin tone can impact black men in the criminal-justice arena. …
Part of the reason may simply come down to how pretty jurors consider a defendant to be, and that being light-skinned and thin (also a factor studied in the research) are seen as more attractive. (source)
More on discrimination in incarceration is here.