Definitions
Fault (bug): a logical defect in a program; difficult to pinpoint. By definition, to be a fault, “it” must cause at least one input to result in failure
Error: mental mistake made by programmer that results in a fault; this is a frequently misused term
Failure: the occurrence of an output value that does not meet the requirements for the input value
Fault size: the number of inputs from the input value space that execute a particular fault and result in failure
Fault density: (same as fault size)