JIRA's Versions report shows a summary of all versions (if any have been created) in a project.
To browse a project's versions,
- On the top navigation bar, click the white triangle next to 'Projects'. The projects dropdown will display.
Tip: If you click on the 'Projects' link instead of the triangle, the summary for your current project will display.
- Click the project that you wish to browse. If it is not displayed in the dropdown, click 'View All Projects' — you will be able to view a list of all projects set up in your JIRA instance and select your project from there.
- Click the 'Versions' tab on the left of the page. A list of versions for your project will display (see screenshot below):
Screenshot: 'Versions' page for a Project

A live version of this example can be seen online.
For each version, see also: