American engineers have been calling small flaws in machines “bugs” for over a century. Thomas Edison talked about bugs in electrical circuits in the 1870s. When the first computers were built during the early 1940s, people working on them found bugs in both the hardware of the machines and in the programs that ran them.
In 1947, Grace Hopper, working on the Mark II computer at Harvard University found a moth stuck in one of the components. She taped the insect in their logbook and labeled it “first actual case of bug being found.” The use of the words “bug” and “debug” soon became a standard.