A subreport it a completely separate report within the main report. It is very useful to create reports with a 1:m correlation. The only difference to the main report is that a subreport has no page header and footer. A subreport can also be marked to be rendered on demand, which means it is not really a part of the resulting report but a separate report reachable by a link.

To add a subreport to the report, click the toolbar button and drag a rectangle in the report design view by pressing the left mouse button and dragging the cursor. After that the dialog "Insert Subreport" appears in that you can configure the name of the subreport and other properties.