<P> Some software bugs have been linked to disasters . Bugs in code that controls the Therac - 25 radiation therapy machine were directly responsible for patient deaths in the 1980s . In 1996, the European Space Agency's US $1 billion prototype Ariane 5 rocket had to be destroyed less than a minute after launch due to a bug in the on - board guidance computer program . In June 1994, a Royal Air Force Chinook helicopter crashed into the Mull of Kintyre, killing 29 . This was initially dismissed as pilot error, but an investigation by Computer Weekly convinced a House of Lords inquiry that it may have been caused by a software bug in the aircraft's engine - control computer . </P> <P> In 2002, a study commissioned by the US Department of Commerce's National Institute of Standards and Technology concluded that "software bugs, or errors, are so prevalent and so detrimental that they cost the US economy an estimated $59 billion annually, or about 0.6 percent of the gross domestic product". </P> <P> The term "bug" to describe defects has been a part of engineering jargon since the 1870s and predates electronic computers and computer software; it may have originally been used in hardware engineering to describe mechanical malfunctions . For instance, Thomas Edison wrote the following words in a letter to an associate in 1878: </P> <P> It has been just so in all of my inventions . The first step is an intuition, and comes with a burst, then difficulties arise--this thing gives out and (it is) then that "Bugs"--as such little faults and difficulties are called--show themselves and months of intense watching, study and labor are requisite before commercial success or failure is certainly reached . </P>

Where did the term bug in software come from