Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V. Penicillin antibiotics are historically significant because they are the first drugs that were effective against many previously serious diseases, such as syphilis, and infections caused by staphylococci and streptococci.

Antibiotics are a type of medicine that has antibacterial properties. The word antibiotic comes from the Greek words anti, meaning against, and bios meaning life. They are used to cure bacterial infections in humans. Bacteria are tiny organisms that cause illness or infection when they gain access to the human body.