Close-quarters combat (CQC) or close-quarters battle (CQB) is a close combat situation between multiple combatants involving ranged or melee combat. It can occur between military units, law enforcement and criminal elements, and in other similar situations. CQB is typically defined as a short duration, high intensity conflict characterized by sudden violence at close range.

A ranged weapon is any weapon that can engage targets beyond hand-to-hand distance, i.e. at distances greater than the physical reach of the user holding the weapon itself. The act of using such a weapon is also known as shooting. It is sometimes also called projectile weapon or missile weapon because it typically works by launching solid projectiles ("missiles"), though technically a fluid-projector and a directed-energy weapon are also ranged weapons. In contrast, a weapon intended to be used in hand-to-hand combat is called a melee weapon.