To be fair the term “debugging” a system predates the computer age, but on September 9, 1947 a famous incident occurred that is memorialized in the Smithsonian National Museum of American History.
Technicians detected an issue in the operation of one of the large calculating computers of the day. They traced the problem to a dead moth in a relay which they carefully removed and taped into their log book. They made the notation “First actual case of bug being found.” Since that day errors in computers and software are still labeled as “bugs.” Now you know!
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