Why is it Called a Software Bug: Origins of the Term in Computing History

Kimberly Perez

macbook pro on persons lap

The term “software bug” has an interesting history that goes back to the early days of computing. A “software bug” refers to an error, fault, or flaw in a computer program that causes it to produce an incorrect or unexpected result or behave in unintended ways. Identifying and fixing bugs is an essential part of the software development process, ensuring that programs run smoothly and accurately perform their intended tasks.

The origin of the term “bug” to describe technical errors pre-dates computers and software, and it was used to refer to a glitch or malfunction in machines in engineering. The term became closely associated with computers in 1947 when an actual moth was discovered trapped in one of the components of the Harvard Mark II computer, causing a fault. The engineers working on the computer recorded this incident, linking the idea of computer errors with an actual “bug.”

Since then, the term has been universally adopted in both hardware and software. Identifying and resolving software bugs is a critical step in the development cycle that helps maintain the functionality, security, and user experience of software across various platforms. Some bugs can be insignificant and quickly addressed, while others may require significant effort and can have profound implications for the software’s performance and reliability.

Software Bugs: A Historical Look

Computer errors are so common they have their own name. But why are they called bugs?

Back in the old days

The idea that machines can have flaws goes back a long way. In the 1800s, Thomas Edison used the term “bug” to describe problems with his inventions. Even earlier, the phrase “bugbear” existed – it meant a scary monster.

The first real “computer bug”

In 1947 something strange happened with an early computer called the Mark II. It wasn’t working right. The engineers on the project eventually found the cause – a moth stuck inside the machine! They carefully taped this moth to their logbook with a note: “First actual case of bug being found.”

This story is where we often think the term “computer bug” comes from. But the word was already in use by engineers before this.

Computer Bug - Courtesy of the Naval Surface Warfare Center, Dahlgren, VA., 1988. - U.S. Naval Historical Center Online Library Photograph NH 96566-KNThe above link is no longer valid on 13.04.2017, the image available here., Public Domain, https://commons.wikimedia.org/w/index.php?curid=165211
The First Computer Bug Moth found trapped between points at Relay # 70, Panel F, of the Mark II Aiken Relay Calculator while it was being tested at Harvard University, 9 September 1945. The operators affixed the moth to the computer log, with the entry: First actual case of bug being found. They put out the word that they had debugged the machine, thus introducing the term debugging a computer program. In 1988, the log, with the moth still taped by the entry, was in the Naval Surface Warfare Center Computer Museum at Dahlgren, Virginia. Courtesy of the Naval Surface Warfare Center, Dahlgren, VA., 1988. U.S. Naval History and Heritage Command Photograph.

Grace Hopper and debugging

Rear Admiral Grace Hopper was a pioneer in computer science. She was part of the team working on the Mark II computer. Hopper helped popularize the idea of a “bug” causing computer glitches. The term “debugging” – fixing software problems – likely came from her influence as well.

Here’s a summary of the history:

1800sThomas Edison uses the term “bug” for technical problems
1947A moth is found stuck in the Mark II computer, causing a malfunction
1950s +Grace Hopper promotes the use of “bug” and “debugging” for computer issues

Key Takeaways

  • A “software bug” is an error in code that leads to unintended program behavior.
  • The term “bug” has origins in engineering and became associated with computers after a 1947 incident.
  • Fixing bugs is critical for the functionality, security, and user experience of software.

Origin and History of the Term ‘Bug’

The term ‘bug’ has a history in engineering and refers to a flaw or glitch within a system. Its use has evolved over time, especially in computing, to describe errors or faults in software.

Early References and Thomas Edison

Thomas Edison, a prolific inventor, used the word ‘bug’ in the late 19th century to describe technical difficulties. He noted these ‘bugs’ as problems to work through during the development of his inventions. Edison’s use of the word suggests that any small issue or glitch that hinders functionality can be seen as a ‘bug’.

Grace Hopper and the Moth Incident

Grace Hopper, a notable figure in the Harvard Computation Laboratory, became a part of history with an event involving a Mark II computer. On September 9, 1947, her team found an actual moth trapped in a relay. This incident, logged as a ‘bug’ in the computer, was a literal example of an insect causing a fault in electronic equipment. The log book from this event is now at the National Museum of American History in the Smithsonian.

Evolution of Terminology in the Computer Age

Since the invention of computers, the term ‘bug’ has grown to describe faults in computer software. Software developers engage in debugging, which is the process of finding and fixing these software bugs. As computer technology has become more complex, so too has the importance of identifying and correcting these errors to ensure software runs effectively. The term is now a standard part of the vocabulary in software development.