An area denial weapon is a defensive device used to prevent an adversary from occupying or traversing an area of land, sea or air. The specific method may not be totally effective in preventing passage, but is sufficient to severely restrict, slow down, or endanger the opponent. Some area denial weapons pose risks to civilians entering the area even long after combat has ended, and consequently are often controversial. An area denial weapon can be part of an anti-access/area denial (A2/AD) strategy.

Anti-Access/Area Denial is a military strategy to control access to and within an operating environment. In an early definition, anti-access refers to those actions and capabilities, usually long-range, designed to prevent an opposing force from entering an operational area. Area denial refers to those actions and capabilities, usually of shorter range, designed to limit an opposing force's freedom of action within the operational area. In short, A2 affects movement to a theater, while AD affects movement within a theater. A2/AD typically refers to a strategy used by a weaker opponent to defend against an opponent of superior skill, although a stronger opponent can also use A2/AD.