The computer “bug” was named after a literal bug found in a computer.
In 1947, computer pioneer Grace Hopper found herself working on a Mark II Computer at Harvard University. It was at this time that her associates discovered a moth had gotten trapped in one of the computer’s relays and was causing an error. The operators removed the moth and taped it in their log book, identifying it as the “first actual case of bug being found.”
Word got out that the team had “debugged” the computer, hence leading to the phrase’s use in computing and pop culture. Hopper readily admitted that she was not there when the incident occurred, but that didn’t stop it from becoming one of her favorite stories. Hopper died of natural causes on January 1, 1992, at the age of 85. For those interested, the offending moth’s remains, along with the original log book, can be seen at the Smithsonian National Museum of American History in Washington, D.C.
And while this is the “modern” use case of finding a computer bug, the original use of the word dates further back in time to Thomas Edison, who in an 1878 letter used the term “bug” to refer to a technological glitch. While he worked on the quadruplex telegraph, he said it needed a “bug trap” to function properly.