The term 'computer bug' became famous in 1947 when a real moth got stuck inside a computer.

On September 9, 1947, operators at Harvard University were using a machine called the Mark II Aiken Relay Calculator. The computer started having errors in a specific part called Relay 70 on Panel F. When the team looked inside, they found a moth stuck between the metal points of a relay. The mechanical movement of the machine had killed the insect. This physical barrier stopped the electricity from flowing through the circuit.The team included Grace Hopper, a famous computer scientist and Navy officer. They used tweezers to remove the moth and taped it into their official logbook. They wrote a note saying it was the first actual case of a bug being found. This logbook is now kept at the Smithsonian Institution in Washington, D.C. While people used the word bug for small flaws before this, this event made the term popular for computers.The Harvard Mark II was a giant machine used by the U.S. Navy to calculate the paths of missiles. It had 13,000 mechanical switches called relays and 113 miles of wire. These computers were kept in large rooms that were not sealed, so dust and bugs could easily get inside. Grace Hopper later helped create COBOL, which was one of the first easy-to-use programming languages. Today, the process of fixing mistakes in computer code is still called debugging.