According to WikiPedia, this is the definition of Print based POD:
“Digital technology is ideally suited to publish small print runs of posters (often as a single copy) when they are needed. The introduction of UV-curable inks and media for large format inkjet printers has allowed artists, photographers and owners of image collections to take advantage of print on demand.
For example, UK art retailer King and McGaw fulfils many of its art print orders by printing on demand rather than pre-printing and storing them until they are sold, requiring less space and reducing overheads to the business. This was brought about after a fire destroyed £3 million worth of stock and damage to their warehouse.
POD fuels a new category of publishing (or printing) company that offers services, usually for a fee, directly to authors who wish to self-publish. These services generally include printing and shipping each individual book ordered, handling royalties, and getting listings in online bookstores. The initial investment required for POD services is lower than for print runs. Other services may also be available, including formatting, proofreading, and editing, but such companies typically do not spend money on marketing, unlike the conventional publishers they disintermediate. Such companies are suitable for authors prepared to design and promote their work themselves, with minimal support and at minimal cost. POD publishing gives authors editorial independence, speed to market, ability to revise content, and greater financial return per copy than royalties paid by conventional publishers.”