Vocabulary

  Software testing has developed its own vocabulary. The meaning of most expressions used is not difficult to guess, and most of them should not be used in a too narrow sense. Nevertheless the most important of them will be listed here:

In [ieee90] four similar definitions are given for an error :

1. The difference between a computed, observed , or measured value or condition and the true, specified, or theoretically correct value or condition. For example, a difference of 30 meters between a computed result and the correct result. 
2. An incorrect step, process, or data definition. For example, an incorrect instruction in a computer program.
3. An incorrect result. For example, a computed result of 12 when the correct result is 10. 
4. A human action that produces an incorrect result. For example, an incorrect action on the part of a programmer or operator.

The meanings of those words overlap, and sometimes it is nearly impossible to decide which of them fits best. Often it is distinguished between the human  action (a mistake), its manifestation (a fault), the result of the fault (a failure), and the amount by which the result is incorrect (the error).