A section is a container for an imposition grid of pages that will be in the correct sequence when folded and bound. However, the actual definition can depend on whether you are discussing a planned product component in the Assembly view or a production component in the Press Runs view. 

Press-run sections

A section on a layout is referred to as a press-run section. (This is also known as a book signature, or in JDF, as a BinderySignature.)
You can manually create a press-run section by adding a template signature or fold pattern to a layout, or creating an imposition for a layout.
After a press sheet is printed and cut, each section is folded and trimmed, and arrives at the finishing equipment as one folded signature.

Product sections

When setting up a book structure in the Assembly view or in the Products list, you organize its text part into sequentially numbered product sections. A product section represents a specific planned page range within a product assembly, which can be imposed or ganged with other product sections on a press run
You can also create press-run sections by autogenerating the press runs from product intent, or by dragging product sections from the Products list.

Multiple sections

Each section on a press-run layout represents one instance of a product section, depending on how you plan your press runs. There are many ways to create a press run with multiple sections, including these examples:

• Renumbering a fold pattern or an imposition on a layout so that it contains two low-folio pages (that is, both are page 1) breaks it into two press-run sections.
• Ganging a product section by dragging it twice to the same press run results in two identical signatures for two copies of the same product.
• You can also gang product sections from different products to create a multisection press run.

Sub-sections (Ribbons)

The concept behind sub-sections (or ribbons) is to allow bindery operations to be accomplished as part of the press running. As the paper flows through the press, the sheet (or ribbon) is cut and then transferred to the top of the next sheet (or ribbon). Then the inline finishing processes cut and fold this to produce a finished result. 

There are two ways to create a press run that has Sub-sections (or ribbons):

• Create a multi-web layout and then copy and paste the web section onto web 1, thus combining them into sub-sections or ribbons. Then, select the extra webs and delete them.
• Create a multi-web layout, save it as a custom fold pattern, and then generate a web press run with the custom fold pattern. Copy and paste the web sections onto web 1, thus combining them into sub-sections or ribbons. The generation process will fill the sheet with ribbons. Delete the extra ribbons from web 1, and then select the extra webs and delete them.