Waterboarding is a form of torture in which water is poured over a cloth covering the face and breathing passages of an immobilized captive, causing the person to experience the sensation of drowning. In the most common method of waterboarding, the captive's face is covered with cloth or some other thin material and immobilized on their back at an incline of 10 to 20 degrees. Torturers pour water onto the face over the breathing passages, causing an almost immediate gag reflex and creating a drowning sensation for the captive. Normally, water is poured intermittently to prevent death; however, if the water is poured uninterruptedly it will lead to death by asphyxia. Waterboarding can cause extreme pain, damage to lungs, brain damage from oxygen deprivation, other physical injuries including broken bones due to struggling against restraints, and lasting psychological damage. Adverse physical effects can last for months, and psychological effects for years. The term "water board torture" appeared in press reports as early as 1976.

Torture is the deliberate infliction of severe pain or suffering on a person for various reasons, including punishment, extracting a confession, interrogation for information, or intimidating third parties.