expert

An expert is a person who has acquired a high level of knowledge or skill in a specific domain, to the point that their judgments and decisions are widely regarded as reliable within that field. Expertise is typically demonstrated through a combination of extended experience, formal credentials, performance records, and the ability to solve complex problems in domain-specific ways. Expertise is often tacit as well as explicit: experts may recognize patterns, cues, and subtleties that novices do not notice, even if they cannot always articulate the underlying rules.

The development of expertise generally requires prolonged deliberate practice, continual learning, and exposure to a wide range of problems. Evaluation of expertise may involve assessments of performance, peer recognition, certifications, or demonstrated results. Experts are often specialized rather than broadly knowledgeable, and their judgments can be influenced by cognitive biases or overconfidence.

In everyday use, experts can be consulted as authorities and may contribute to research, policy, or practice. In computing, the term is also used in AI to describe systems that simulate or reproduce domain knowledge in rule-based or probabilistic form.