Below are the state of any bug by which bug goes through during test life cycle.
1.NEW : Tester Found new bug in the application.
2.Assigned : Tester assign Bug to the developer.
3.Open : Developer is fixing the bug .
4.Fixed : Developer has fixed the bug.
5.Retest : Tester verify the bug.
6.Closed/Reopened : If bug is fixed then tester closed the bug otherwise tester reopened the bug and assign it to the developer.