A defect is a shortcoming, an imperfection or a flaw in any object or system.
In terms of software testing, Defect Severity is the impact that a defect has on either the development or execution of any program. It is the degree of impact that a defect has, on the application. The higher the degree of impact or severity the more detrimental the error will be. The honest opinion is that Defect Severity in software testing depends on how important the tested function is.
Every software undergoes comprehensive testing before it can be launched. The purpose of these various tests is to find and remove defects. When it comes to testing, it can be done by either the code developers themselves or the testers, as the case may be.
Defects are classified into 4 main types based on the severity of their impact. These are:
Great caution needs to be exercised while checking for the severity of a defect. This is because even a minor oversight can make a critical error trivial and vice-versa. Also, when it comes to the war of words between the developers and the testers, it has often been seen that the developers do not agree with the findings of the testers in terms of the impact that a defect can have. This problem can, however, be overcome by setting some mutually agreed upon standards.
Calculating the Defect severity is the best way of prioritizing corrective action and its implementation. Obviously, a critical error needs to be addressed first and foremost, subsequently moving down the line.