This document discusses liquid explosives and their use by terrorists. It describes common types of liquid explosives like nitroglycerin and nitroglycol. It explains how liquid explosives work using shock, friction or heat. It discusses how liquid explosives became a major threat for air transportation as terrorists could conceal explosive liquids in drink bottles or cosmetic containers that could be detonated easily. It concludes by noting two dangerous homemade explosives, HMTD and TATP, that can be made from common household chemicals and are very sensitive.