The Dunning-Kruger effect is a cognitive bias whereby people with limited knowledge or competence in a given intellectual or social domain greatly overestimate their own knowledge or competence in that domain relative to objective criteria or to the performance of their peers or of people in general.

According to the researchers for whom it is named, psychologists David Dunning and Justin Kruger, the effect is explained by the fact that the metacognitive ability to recognize deficiencies in one’s own knowledge or competence requires that one possess at least a minimum level of the same kind of knowledge or competence, which those who exhibit the effect have not attained.”

Although not scientifically explored until the late 20th century, the phenomenon is familiar from ordinary life, and it has long been attested in common sayings—e.g., “A little knowledge is a dangerous thing”—and in observations by writers and wits through the ages—e.g., “Ignorance more frequently begets confidence than does knowledge” (Charles Darwin).”