The story goes like this:

Back when computers still consisted of vacuum tubes, a system went down one day and people started investigating the cause. They found that a moth was stuck in the computer which fouled it up. When asked what was wrong the tech said "There was a bug in the computer", and since then the term has stuck.

Is that a mostly true story, and if so is that where the terms "computer bug" and "debugging" came from?

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    You may want to add a source for that quote. – nico Jul 31 '12 at 17:53
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    Etymology - not to be confused with entomology. – Andrew Grimm Aug 1 '12 at 12:29
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    @AndrewGrimm - Obligatory: xkcd.com/1012 – Jamiec Aug 1 '12 at 15:27
  • I remember reading that when I was in college for a computer programming degree. The text book that we used had pictures of the actual bug (a really big moth) stuck in the guts of one of those room sized computers that was top of the line at the time. I dont remember the name of the text book, that was a really long time ago, but yes, thats what they do/did teach at that time. – user15111 Aug 22 '13 at 13:38
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    @Jamiec - mere chance, that the superhero in this xkcd is a grasshopper (Grace Hopper)? – Jürgen Thelen Jan 26 '14 at 17:45

No; however, this is partly due to semantics, the actual log entry is as follows:

First actual case of a bug being found.

First Computer "Bug"

This is a bit of a tongue-in-cheek reference to the term "bug" that was in use at the time meaning:

The term "bug" is used to a limited extent to designate any fault or trouble in the connections or working of electric apparatus.

Whose definition is courtesy of Hawkin's New Catechism of electricity from 1896. So we know the term was already around at the time and from the log entry we can deduce that other mechanical failures were likely called "bugs" as well.

However, it is apparently the first case of an actual bug being stuck in the computer.

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    yes, the key word is "actual" – Nikko Sep 18 '12 at 19:47
  • What's with the down vote? – rjzii Jun 10 '13 at 22:24
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    It might be worth mentioning that, contrary to the story as presented in the question, this was before computers started to use vacuum tubes. They used relays (which, being mechanical, were more prone to be affected by insects). – Emil Jeřábek Nov 21 '18 at 15:45

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