Sep 9, 1947 CE: World’s First Computer Bug

Sep 9, 1947 CE: World’s First Computer Bug

On September 9, 1947, a team of computer scientists reported the world’s first computer bug—a moth trapped in their computer at Harvard University.


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English Language Arts, Experiential Learning

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On September 9, 1947, a team of computer scientists and engineers reported the world’s first computer bug. A bug is a flaw or glitch in a system. Thomas Edison reported “bugs” in his designs as early as the 1800s, but this was the first bug identified in a computer. Today, software bugs can impact the functioning, safety, and security of computer operating systems. “Debugging” and bug management are important parts of the computer science industry.

This bug, however, was literally a bug. “First actual case of bug being found,” one of the team members wrote in the logbook. The team at Harvard University in Cambridge, Massachusetts, found that their computer, the Mark II, was delivering consistent errors. When they opened the computer’s hardware, they found ... a moth. The trapped insect had disrupted the electronics of the computer.

Among the team who found the first-reported computer bug was computer-language pioneer Dr. Grace Hopper. She is often given credit for reporting the bug, but that is not true. She was, however, the person who likely made the incident famous.

Hopper, who earned a mathematics doctorate from Yale University in 1934, was one of the first computer programmers. Dr. Hopper invented the first English-language data-processing compiler, which laid the foundation for the development of machine-independent programming languages, like COBOL that she helped develop.

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National Geographic Society
National Geographic Society
Last Updated

October 19, 2023

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