Primary packaging is the material that first envelops the product and holds it. This usually is the smallest unit of distribution or use and is the package which is in direct contact with the contents.
Secondary packaging includes cardboard cartons, cardboard boxes, cardboard/plastic crates, trays, paperboard cartons, shrink wrapped bundles, trayed PET bottles held with shrink wrap, taped or glued cardboard cartons containing cans of food, Pouches of food, Consumable material.
Tertiary or transit packaging is used for bulk handling, warehouse storage and transport shipping. The most common form is a palletized unit load that packs tightly into containers.