A “bug” is an error or defect in software or hardware that causes a program to malfunction. Often a bug is caused by conflicts in software when applications try to run in tandem. One well-known classification of software bugs is the unusual software bug which includes the heisenbug, bohrbug, mandelbug and the schroedinbug.
History of the Phrase
According to folklore, the first computer bug was an actual bug. Discovered in 1945 at Harvard, a moth trapped between two electrical relays of the Mark II Aiken Relay Calculator caused the whole machine to shut down.