Harvard psychiatrist Chester Pierce introduced the term in 1970 to describe the everyday insults and dismissals Black Americans experienced from white Americans. Psychologist Derald Wing Sue and colleagues expanded it in a 2007 article, describing microaggressions as brief, common slights, intentional or not, that send hostile or negative messages to people of color.
Common examples include asking an Asian American where they are "really" from or telling a Black professional they are "so articulate." Others include clutching a bag when a Black man walks by, or mispronouncing a name after being corrected. Each moment may seem small, which is why the person who says it often denies any harm.
The harm comes from repetition. Researchers link the steady accumulation of microaggressions to stress, anxiety and physical health effects, a pattern related to weathering. Critics argue the term is too broad, but the research focus is on patterns, not single comments. The "micro" refers to the scale of each act, not the size of its impact.