链球菌, or Streptococcus, is a genus of bacteria that are commonly found in the human body, particularly in the throat and on the skin. These bacteria can be classified into different groups based on their characteristics, with some being harmless while others can cause infections. Some types of 链球菌 are responsible for illnesses such as strep throat, scarlet fever, and pneumonia. They can spread through respiratory droplets or direct contact with infected wounds. Proper hygiene and medical treatment are essential to prevent and manage infections caused by these bacteria.