An Expert Witness is a person who is an authority in a specific field and provides an opinion as evidence in a court of law. Expert Witnesses may come from a variety of professions, such as medicine, engineering, psychology, or accountancy, and must have specialized knowledge and experience in the relevant area. Expert Witnesses are usually called upon to give their opinion on technical matters and to explain to a court the technical aspects of a case. There are three types of Expert Witnesses: Fact Witnesses, Expert Witnesses, and Lay Witnesses. Fact Witnesses provide testimony based on their firsthand knowledge, while Expert Witnesses provide an opinion based on their specialized expertise. Lay Witnesses provide testimony based on their personal knowledge or experience, rather than specialized expertise.