Print on Demand
It is no coincidence that the concept of POD appeared at the time of rapid growth in ownership of personal computers allowing independently minded writers to break free from what many saw as the shackles of traditional printing. The methodology supporting book publication that existed before POD worked well when sales were good but otherwise was not helpful to the unknown writer. The initial print run would invariably run into many thousands of copies of a single title which was only financially viable if a significant proportion of the books were sold at cover price. If the book flopped then the publishing company would face financial loss which is why they preferred known writers who could almost guarantee success.
In POD the book is stored as a digital file rather than a physical entity so that when an order is received a computer selects the relevant file and sends that to a dedicated printer to produce a single copy in a matter of minutes. Clearly this implies that each copy of a book is more expensive to print than would be the case with a large print run but that is balanced by savings elsewhere. No large sum of money is invested in the publication process so there is no danger of significant financial loss. There are no storage costs and retail outlets which would take a percentage of the cover price are bypassed. A publisher no longer has to deal with book returns and there is no need to write-off pulp stock when a book clearly fails to sell. Such a book can continue in print indefinitely.