Waterboarding is a procedure that has been used to make people confess. It has been used for a long time. Today, many people see it as a form of torture.
The victim is tied onto a table or wooden board. The questioner has a helper, whose job it is to pour water on the victim's nose and mouth through a towel or cloth, to make it difficult for him to breathe. If and when the victim is supplying answers that the questioner deems acceptable, the victim (ideally) is permitted to breathe. Waterboarding has been in use in Guantanamo Bay and has been a major political fiasco.