Antibiotics are medicines used to treat infections caused by bacteria. They work by killing or preventing the growth of bacteria, thus stopping the infection. Antibiotics are an important tool in modern medicine, used to treat diseases such as pneumonia, strep throat and tuberculosis. They are also used to prevent infection in some cases, like after a surgery or after a wound has been cleaned. By helping to fight off bacterial infections, antibiotics have saved countless lives and are essential for keeping people healthy.