What is a defect and what is defect management ?

Defects determine the effectiveness of the testing what we do. If there are no defects, it directly implies that we do not have our job. There are two points worth considering here, either the developer is so strong that there are no defects arising out, or the test engineer is weak. In many situations, the second is proving correct. This implies that we lack the knack.

For a test engineer, a defect is:
- any deviation from specification.
- anything that causes user dissatisfaction.
- incorrect output.
- software does not do what it intended to do.

Software is said to have bug if it features deviates from specifications.
Software is said to have defect if it has unwanted side effects.
Software is said to have error if it gives incorrect output.

Categories of Defects
All software defects can be broadly categorized into the below mentioned types:
- errors of commission : something wrong is done.
- errors of omission : something left out by accident.
- errors of clarity and ambiguity : different interpretations.
- errors of speed and capacity.

Types of defects that can be identified in different software applications are conceptual bugs, coding bugs, integration bugs, user interface bugs, functionality, communication, command structure, missing commands, performance, output, error handling errors, boundary-related errors, calculation errors, initial and later states, control flow errors, errors in handling data, race condition errors, load conditions errors, hardware errors, source and version control errors, documentation errors and testing errors.