In the field of psychology, the **Dunning–Kruger** effect is a cognitive bias wherein people of low ability suffer from illusory superiority, mistakenly assessing their cognitive ability as greater than it is. The cognitive bias of illusory superiority derives from the metacognitive inability of low-ability persons to recognize their own ineptitude.
The DK effect is important to understand for software developers. It can be observed among developers of all ages. This is more prominent among beginners and intermediate level developers. After the initial struggle, they might get overconfident about a language or their designs. This leads them to underestimate the complexity of system requirements or, worse, hampers them coming up with better software designs. For more experienced developers, they seem to have gained wisdom over the years. They are more humble and better at judging the system complexity. (This might not be true to all senior developers though.)
DK Effect is exactly opposite of [Imposter Syndrome](https://en.wikipedia.org/wiki/Impostor_syndrome). You need to strike the perfect balance between both of these for your professional growth.