The Dunning–Kruger effect is a theoretical cognitive bias which was described by David Dunning and Justin Kruger in a 1999 psychological study and paper.
The study suggests that people with a low level of ability at a task are likely to overestimate their ability of the task. The proposed reason for this bias is that sufficient awareness of the complexity of a problem or domain is required for a person to be able to make an informed opinion of their capability to work in that domain.
A form of illusory superiority
related: cognitive bias