Though tourniquets were likely in use since Roman times, the term “tourniquet” was originally turned by Louis Petit, the 18th century inventor of the screw tourniquet.  Though numerous design advancements have occurred and new devices have been made in the centuries that have followed, the basic principles of tourniquet use are essentially unchanged.  A tourniquet applies an external pressure to a limb (usually) that exceeds the arterial pressure in that extremity.  In this way the inflow of arterial blood to an extremity is stopped.  For a surgeon, in the setting of a prospective extremity surgery, this allows for the creation of a bloodless operative field.  For Emergency Medicine providers, tourniquets can aid in the exploration of extremity wounds, allowing the identification of injuries to tendons, joints, and vascular structures.  And perhaps most importantly, tourniquets applied proximal to the site of penetrating traumatic extremity injuries can cease bleeding from arterial injuries.