It simply means a method of finding bugs in the application which is under test. In a software project , once a module is completed by a developer they first do unit testing and then they pass it on to the Qa team.
Now, Qa will start testing the module and check for Alignment issues,functional issues,etc and if found they will log these issues based on severity/ Priority of the issue.
So overall, Logging a defect is simply creating a bug and specify the status as Open,setting the priority & severity.
Testers also use different tracking tools for logging the defects.Once its logged , they are then assigned to the Development team.If issues get fixed,they are closed else its Reopen/Reassigned etc by the Qa.
It is simply a method of managing the bug cycle.
In SDLC , when an application or product is supposed to be deliver to the client,it is tested several times by the testing team. When a reported bug is fixed by Development team , it is then ask to the Qa team to further verify the defect.
Before these several defects can be closed down,it is visited by several times by different people.So to ease this defect management process, different tracking tools are used.
Benefits of Tracking tools:
It is more organized and effective way of managing the defects.
It gives the centralized overview on the defects and with the bug details.
It provides the history of the defect management.
It provides the same platform for all the members added to the team to track the progress of the defects.
It allows the user filter the reports based on Severity,priority,iteration etc.
In total, it gives the overall progress of the Project and helps the senior management also to let the client know when the product/application can be delivered to them.