Copper is the only metal that has been scientifically proven to have anti-bacterial properties. Copper has the ability to kill bacteria by damaging their cell walls, which leads to the death of the bacteria. This is why copper is often used in items that need to be kept clean and hygienic, such as door handles, kitchen utensils, and medical equipment. Copper's anti-bacterial properties make it a popular choice for preventing the spread of germs and infections.