In 1928, the Scottish scientist Alexander Fleming made a discovery that changed medicine forever. He noticed something unusual in his laboratory.

Fleming had left some cultures of bacteria on his workbench. When he returned, he saw that a mold called Penicillium notatum had contaminated the plate.

He observed that the mold killed or stopped the growth of the harmful bacteria. This was the first step toward a powerful antibiotic.

Fleming named the substance penicillin. At first, the amount he produced was too small for practical use.

Later, other researchers, including Howard Florey and Ernst Chain, worked on methods to mass-produce the drug during World War II.

With large-scale production, penicillin became available to treat wounded soldiers and civilians. It saved countless lives.

The discovery of penicillin marked the beginning of the era of antibiotics. It changed the way doctors fought diseases.

Today, penicillin and its derivatives remain essential in modern healthcare, even though some bacteria have developed resistance.