JIRA's Components report shows a summary of all components (if any have been created) in a project.
To browse a project's components,
- 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 'Components' tab on the left of the page. A list of components for your project will display (see screenshot below):
Screenshot: 'Components' page for a Project

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