Real and Demonstrative Evidence
Real evidence is a thing. Its existence or characteristics are considered relevant and material to an issue in a trial. It is usually a thing that was directly involved in some event in the case, such as a murder weapon, the personal effects of a victim, or an artifact like a cigarette or lighter belonging to a suspect. Real evidence must be relevant, material, and competent before a judge will permit its use in a trial. The process whereby a lawyer establishes these basic prerequisites (and any additional ones that may apply), is called laying a foundation. In most cases, the relevance and materiality of real evidence are obvious. A lawyer establishes the evidence's competence by showing that it really is what it is supposed to be. Establishing that real or other evidence is what it purports to be is called authentication.
Evidence is considered "demonstrative" if it demonstrates or illustrates the testimony of a witness. It is admissible when it fairly and accurately reflects the witness's testimony and is otherwise unobjectionable. Maps, diagrams of a crime scene, charts and graphs that illustrate profits and losses are examples of demonstrative evidence.