Anti-de Sitter space is a type of geometric space used in theoretical physics, particularly in the study of general relativity and string theory. It is characterized by a constant negative curvature, which means it has a saddle-like shape. This unique geometry allows for interesting properties, such as the existence of a boundary at infinity. In Anti-de Sitter space, the laws of physics can behave differently than in flat or positively curved spaces. It is often used in the context of the AdS/CFT correspondence, a conjecture that relates theories of gravity in Anti-de Sitter space to quantum field theories on its boundary. This relationship has profound implications for understanding quantum gravity and black holes.