In Tracker, release markers are used to help show stories in specific releases or milestones you are working toward. They can also be used to separate and organize different groups of stories in your Icebox.
For instance, you could use a release marker to indicate bugs that need to be prioritized by the project owner, features for upcoming epics that are awaiting prioritization, or to help separate various feature sets or themes. You can use an “Inbox” marker so that newly added stories are more obvious.
If you find that bugs in the Icebox are not going to be fixed for any reason, you may choose to handle them with a different process than stories that follow a normal workflow. See some tips for handling bugs in Tracker’s workflow.