Penicillin is an effective antibiotic. Penicillin was the first antibiotic, discovered accidently. When Alexander Flemming was working on staphyloccous bacteria, he found that on a dirty glass slide, mould were grown, due to which staphylococci could not grew upon it. He found that it happened due to a special chemical released by fungus. Since this special chemical was produced by fungus Penicillium notatum, he named this special chemical as Penicillin. Later, Ernst chain and Harward Flore confirmed it as a potent and effective antibiotic. This antibiotic was used to cure American soldiers during IInd World War on large scale.