How are the defects classified?

All defects are not the same type. Some defects may result in system crash. Some defects may be very minor. So, the defects need to be classified based on its impact on the functionality of the software. There are various ways in which we can classify.

Severity Wise

Major: A defect, which will cause an observable product failure or departure from requirements.
Minor: A defect that will not cause a failure in execution of the product.
Fatal: A defect that will cause the system to crash or close abruptly or effect other applications.

While recording the defects in a defect log sheet, the severity of the defects also needs to be noted. IF a critical defect is present in the code, then the software is not ready for delivery. Only a few major defects are allowed. Similarly, a threshold needs to be kept on the number of minor defects. As the threshold depends on the application, the project manager/test team member has to use the judgement in fixing the thresholds on major and minor defects. After analyzing the test report, the project manager needs to decide whether the software is ready for delivery or not.