Defect (Bug) Life Cycle

A Defect/Bug Life Cycle is made up of series of phases.

1. New
    When the bug is identified and logged in bug tracking tool for the first time, its state will be "NEW".
2. Open / Closed
    After a QA has posted a bug, the QA lead validates the bug. If bug is valid then he changes the state as "OPEN" and if the bug is invalid then the lead changes its state to "CLOSED".
3. Assign
    After QA lead changes the state as "OPEN", he assigns the bug to corresponding developer or developer team lead and the bug status is changed to "ASSIGN".
4. Rejected:
    If the developer feels that the bug is not valid or it has some technical limitations and cannot be fixed, he rejects the bug. He changes the state of bug to "REJECTED".
5. Duplicate:
    If the bug is logged is repeated twice or the two bugs reported has alike results and steps to reproduce, then one bug status is changed to "DUPLICATE".   
6. Deferred:
    If the development team lead decides to fix the bug in next release due to lack of time or the priority of the bug is low then he changes the state to "DEFERRED", which is later changes to "ASSIGN" when the bug is taken in consideration to be fixed.
7. InTest
    Once the developer fixes the bug, he assigns the bug to the testing team for next round of testing. Before that he changes the state of bug to "IN TEST". It specifies that the bug has been fixed and is released to testing team.
8. Verified
    Once the bug is fixed and the status is changed to "IN TEST", the tester tests the bug. If the bug is not reproducible in the software, he changes the status to "VERIFIED".
9. Reopened
    Once the bug is fixed and the status is changed to "IN TEST", the tester tests the bug. If the bug is reproducible in the software, he changes the status to "REOPENED".
10. Closed
    After the bug status is changes to "REJECTED" or "DUPLICATE" or "VERIFIED" the QA Lead verifies the comments added by the development or Testing team. When he is satisfied with the comments he changes the state to "CLOSED".

Note: There are different process and methodologies followed in various organizations. The above content is as per my experience in industry so far.

Please feel free to write comments if you like my post or else if your opinion is different or you may like to add any more points in them.