An expert witness is a person with specialized knowledge or expertise in a particular field, such as medicine, engineering, or finance. They are called upon in legal cases to provide their professional opinion or analysis, helping the court understand complex issues that require expert insight. Their testimony can significantly influence the outcome of a trial. In legal proceedings, expert witnesses may present findings, explain technical details, or offer opinions based on their experience. They are often used in cases involving personal injury, criminal defense, or intellectual property, where their expertise can clarify facts and support arguments for either side.