Hand sanitizer (also known as hand antiseptic, hand disinfectant, hand rub, or handrub) is a liquid, gel or foam generally used to kill the vast majority of viruses/bacteria/microorganisms on the hands.[3][4] In most settings, hand washing with soap and water is generally preferred.[5][6][7] Hand sanitizer is less effective at killing certain kinds of germs, such as norovirus and Clostridium difficile, and unlike hand washing, it cannot physically remove harmful chemicals.