Lots of words have different meanings in the tech world. Think about words such as mouse, Python, worm, virus, or cookie. If you didn’t skip your language lessons, you know these are called homonyms. Also known as words with the same spelling and pronunciation, but with two or more meanings. The word “bug” is also a homonym, referring to either the insect or a system error. So, what happens when a bug (the insect) is the root cause of bugs (systems errors) in a program? Well, one of the teams of computer scientists from Harvard went through this in 1947. On the 9th of September, they spotted a real computer bug (while dealing with other bugs). 

Due to this event, the 9th of September became known as International Tester’s Day. But, it’s important to note this wasn’t the first time someone used “bug” as a reference for system errors. Thomas Edison first used the word to describe glitches or flaws in his inventions back in the 1870s. You can see in one of Edison’s letters (attached below) that he used “bug” while referring to a problem in his invention. Fun fact: this letter was auctioned for 12.500 $ in 2018.

You were partly correct, I did find a ‘bug’ in my apparatus, but it was not in the telephone proper. It was of the genus ‘callbellum‘. The insect appears to find conditions for its existence in all call apparatus of telephones.

real computer bug

One of Thomas Edison’s Letters (3rd of March 1878)


The first case of a real computer bug

The first computer bug was a moth. And it was trapped inside the Harvard Mark II, an electromechanical computer built under the guidance of the computer science pioneer Howard Aiken. While working on it, team members noticed the computer reported errors consistently. Nothing managed to stop the errors from popping, so they considered opening the computer’s hardware. While they were no strangers to dealing with bugs in their programs, discovering a real bug that caused the errors came as a bit of a shock. According to the Computer History Museum in Mountain View, California, the team recorded the first case of a real computer bug in Harvard Mark II’s logbook on September 9th, 1947, at 3:45 pm. 


real computer bug

Log entry describing the first case of a real computer bug displayed at the Smithsonian Institution’s National Museum of American History


After finding the moth, someone in the team extracted it and taped it to the logbook. “First actual case of bug being found” – the sentence below the moth. Today, the logbook with the taped moth is displayed at the Smithsonian Institution’s National Museum of American History. There’s a bit of debate over who made the discovery and the logbook entry. Some claim that Grace Murray Hopper, the computer science pioneer, should get the credit for this. Others say she was among the ones who helped draw attention to this happening, as she was part of the team (but not present when the event occurred). And, according to the item’s description at the Smithsonian, it “was probably not Hopper’s”. While we don’t know for sure who discovered the first real computer bug, this story is an excellent icebreaker for when you’re around tech enthusiasts. 


Final Thoughts

This is the first case of a real computer bug. But, this is not the moment when the tech world coined the word “bug”. If you further read on this topic, you’ll notice it’s a common mistake made in some articles, videos, podcasts, and so on. Whenever you see these two events interlaced, remember that Thomas Edison takes credit for the word’s tech meaning. Because he used it in reference to system errors way before the discovery of the first real computer bug. And, if you’re conflicted on this, check Edison’s letter one more time. 

Besides this, when diving deeper into the topic, it’s important to keep in mind that it was not Grace Hopper’s finding. Because she was part of the team and helped popularize the discovery of the first real computer bug, some associate her with the discovery as well. Check out the Software Bug Stories podcast – you’ll find a quick 4-minute episode on this topic that explores the info shared above a bit more. Thus, what would you do if you happened to encounter a real computer bug in your program? Because taping it to your logbook might not be enough to guarantee your place in museums.