The purpose of folding varies, depending on (a) personal choices, and (b) constraints placed on the size and appearance of your printed product. From a physical consideration, folding paper produces a smaller, more compact product, containing all the information and attributes of the unfolded sheet of paper. Folding paper on this basis produces a finished document that may be easier to handle; that can be inserted into a smaller space; or stored in a smaller space, for example a pocket.
Folding creates curiosity! You can imagine a visual design and well-chosen words, enticing a viewer to “open up and find out more” or “discover within” - a great technique for marketing, entertaining and educating.
Folding produces 4 or more panels on a page. A single fold, for example, produces 2 panels alongside each other, and on each side of your sheet of paper. So as such, the fold produces lines and borders, making up rectangles (or other shapes), each of which may contain a category of total information being communicated to the reader/viewer. This supports and enhances the graphic design of the document.
Graphic designers - remember to accommodate the thickness of material and the need to reduce the width of the “tucked-in” panel, 2 to 3 mm narrower than outer panels. Also, folding is not simply folding when thicker, or heavier stock is used; or when paper “grain” direction is encountered as a technical issue. In these cases, pre-creasing or scoring of the heavier or grainy paper is required. The important considerations here are to select the appropriate paper weight for your printed product; and to recognise that additional cost and production time may be encountered under these circumstances. Nothing that cannot be discussed and resolved at the early planning and quoting stage of your printing project.