If you have JIRA Agile (formerly GreenHopper) version 6.0 or newer installed, it will show additional Structure tab in the issue details panel on Scrum and Kanban boards.
Structure tab displays the standard Structure widget that lets you quickly identify, where in the structure is selected issue located. The widget is by default in Pinned Issue Mode, highlighting the position of selected issue and its sub-issues. You can un-pin selected structure by clicking Pin button on the toolbar or hitting Ctrl+.
Due to rather constrained horizontal space, Structure initially displays only Key and Summary in the Agile tab. However, you can add more columns if needed. (And get a larger display!)
When you click on another issue on an Agile board, Structure widget automatically selects that issue in structure, and, in pinned mode, pins that issue instead of previously selected.
You can switch to viewing a different structure using structure selector.
You can also edit all fields inline in the structure widget, if space allows. After editing is done, Structure signals JIRA Agile to reload the page and you will see the updated values on the board.
Only the users who have access to Structure will see the Structure tab on Agile boards.