An "expert" is someone who has a deep understanding and extensive knowledge in a specific field or subject. This expertise often comes from years of study, practice, and experience. For example, a doctor is an expert in medicine, while a software engineer is an expert in computer programming. Their skills allow them to solve complex problems and provide valuable insights. Experts are often sought after for their opinions and advice. People rely on them to guide decisions, whether in science, art, or business. Their ability to analyze situations and offer solutions makes them invaluable resources in their respective areas of expertise.