The active ingredient in bleach is sodium hypochlorite, or NaClO. Bleach is an important cleaning and disinfecting solution because it is inexpensive, readily available and highly effective.
Sodium hypochlorite disinfects surfaces by denaturing proteins in microorganisms, causing them to die. Bacteria, fungus and viruses are all easily killed using bleach. Stains on clothing are removed using bleach, because bleach oxidizes the stain. Bleach also oxidizes dyes, causing permanent damage. Because bleach is so effective, cautionary measures are taken, including the use of rubber gloves and working in a well-ventilated area. Diluting bleach with cold water is most effective, because sodium hypochlorite is deactivated when mixed with hot water.