Staphylococci are a group of bacteria that are commonly found on the skin and in the noses of healthy individuals. They are spherical in shape and often appear in clusters resembling grapes. While many types of staphylococci are harmless, some can cause infections, particularly when they enter the body through cuts or other openings. One of the most well-known species is Staphylococcus aureus, which can lead to various infections, including skin infections, pneumonia, and food poisoning. Some strains of Staphylococcus aureus, such as MRSA (methicillin-resistant Staphylococcus aureus), are resistant to certain antibiotics, making them more challenging to treat.