A persistent error in software or hardware. If the bug is in software, it can be corrected by changing the program code. If the bug is in hardware, a new circuit has to be designed, and the erroneous chip has to be replaced.
Although the derivation of bug is generally attributed to a moth that was found squashed between the relays of Harvard University's Mark II electromechanical calculator in the 1940s, the term actually goes back to the 1800s to refer to flaws in mechanical systems. See buggy
, bug fix
, software bug
and Web bug
. Contrast with glitch
A Note from the Author
On October 19, 1992, I found my first "real bug." When I fired up my laser printer, it printed blotchy pages. Upon inspection, I found a bug lying belly up in the trough below the corona wire. The printer worked fine after removing it!