The Story About “Bug”


Don’t let the bugs bite you.

Did you know that the term “bug” is established in informal engineering terminology long before computers had their breakthrough? You probably say it dozens of times each (work)day and don’t think about it. But why do we use that word in particular? Why “bug”? Why not “mistake”, “issue”, or “pest”?

The story about the origin of the term is quite long and a bit blurry, but luckily, it’s out there, and we can share it with you.

So, why do we call it “bug”?

Officially, the origin of the term “computer bug” dates to 9th of September 1947.

Earlier that year, Grace Hopper joined the team at the Harvard Faculty to work on the Mark II and Mark III computers. Her team found an error in a relay on Mark II and the error turn out to be a bug. And we are talking about a real insect here. A moth managed to enter the room during the night and drawn by the light and heat of computer he got caught up in relay, causing a glitch.

Hopper taped the insect in the Mark II’s logbook, alongside notes explaining what happened, which led the other team members (including William “Bill” Burke) to coin a term “bug” for all mistakes and issues computer program can have.

There is more

Maybe the team at Harvard can take credits for popularising the term in the IT industry, but as we mentioned, it came long before the invention of modern computers.

The story goes all the way back to 1800s.

There are no records to prove that people used the term “bug” to describe some mechanical error in the early 19th century, but they were familiar with the concept. There is a letter from 1843 wrote by Ada Lovelace, in which she spoke about program “cards” that are not working correctly. She wasn’t using the word “bug”, but clearly, she was talking about it.

Somewhere around that time, “bug” became a popular term for mechanical faults whose source was yet to be identified, isolated and corrected. The mid-1800s roughly mark a starting point for frequent use of the word in engineering jargon, but the first record of it dates to a letter from 1878, written by none other than Thomas Edison. In the letter, he notes: “You were partly correct, I did find a ‘bug’ in my apparatus, but it was not in the telephone proper.”.

The linguistic origin of the term is believed to be derived from the Middle English word “bugge” which is in the base of terms “bugbear” and “bugaboo”. It is also interesting to look at the word “goblin” (“Bögge” Low German) which was used by RAF pilots in WW2 to describe some mechanical malfunctions.

By 1963 both the terms “bug” and “debugging” were so well-known that they were mentioned in the Compatible Time-Sharing System (CTSS) manual without any particular explanation of their meanings.

Nothing has changed since then, except for the fact that “bug” became widely popular outside the industry and highly relatable to programming, so now when someone hears you say it, they might not understand what are you talking about, but they will know for sure you work in IT.