bug

A software bug is a design defect (bug) in computer software. A computer program with many or serious bugs may be described as buggy.
The effects of a software bug range from minor (such as a misspelled word in the user interface) to severe (such as frequent crashing).
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".
Since the 1950s, some computer systems have been designed to detect or auto-correct various software errors during operations.