One of the challenges all software development organizations face is how to handle the defect-tracking (also known as "bug" tracking) process. Unfortunately, often, little thought is put into designing and implementing such a system. Among the reasons that a well-designed defect-tracking system is necessary:
Traceability You need to know what areas of the system produce the most defects.
Accountability Do you have weaker developers and/or QA engineers? For
example: a developer who writes sloppy code will cause more defects, and a QA engineer who lacks attention to detail may miss a critical bug during the testing process.