Offset litho prints from a static image carrier (plate), and every impression is the same. If an impression is different, you did something wrong. Because of the nonproductive period of press setup called "makeready," short-runs are not economically justified for offset litho. But, because makeready is absorbed into each printed unit, unit costs decline as run lengths increase. A newer offset system may reduce makeready, but it will always exist.

Digital printing includes only those toner and inkjet technologies that regenerate the image for each impression. Thus, every impression can be different. All printing today uses digital technology, but digital printing specifically refers to the impression regeneration. The advantages are electronic collation (printing a book's pages in order), versioning (different book versions), personalization and one-off printing. Digital printing unit costs remain constant over all run lengths.

A major difference between the two is that digital printing has no makeready. Theoretically, with digital printing, you can have your book(s) almost immediately, or on-demand. Some use the term on-demand as a euphemism for "fast." The decision to print digitally or by offset usually is based on run lengths—shorter runs go digital, and all other runs go offset.

On-demand vs. Short-run

On-demand means the book is printed when an order is received, and no physical inventory generally exists. On-demand often is called print-on-demand (POD).

Short-run generally means less than 1,000 books, which may be printed digitally or by offset. Digital printing loses some cost advantage as run length increases, although newer, roll-fed inkjet printing systems are pushing digital run lengths higher.

I contend that short-run should mean one to 20, medium-run 21-100, and long-run anything beyond 100. Others say short is up to 50, medium is up to 1,000, and long is more than 1,000. Digital printing technology is advancing rapidly, and this is changing traditional cost relationships.

Cut-sheet and Roll-fed

Cut-sheet (or sheet-fed) printers offer excellent halftone quality for monochrome and are designed for duplex printing with expanded substrate choices. They are best for short-runs. Some sheet-fed printers use paper rolls that are cut into sheets as the paper enters the printer—that does not make it roll-fed.

Roll-fed (or web-fed or continuous feed) printers speed improvements and print on wider webs (supporting three-up impositions). They can generally handle lower substrate weights than cut-sheet, and print longer (short) runs.

The 'Long Tail' and 'One-sies'

The "long-tail" term has gained popularity as a retailing concept describing the strategy of selling a large number of unique items in very small quantities, and selling fewer items in large quantities.

The distribution and inventory costs of businesses applying this strategy allow profit from selling small volumes of hard-to-find items to many customers, in addition to selling large volumes of a reduced number of items. As long as you can cost-effectively print one book, there is a never-ending market for "one-sies."

Scholarly books (or other niche books), self-published books, memory or photo books, backlist and out-of-print books have long-tail possibilities. One example relates to Google Books. Google scanned millions of books in libraries worldwide. I found one and ordered a hard copy via Amazon.com. Think about this: Millions of old books have a renewed life because of one-off printing.

Publishers gamble on every book. The rules have changed in terms of what sells, and it is difficult to forecast demand. Publishers traditionally focus on unit cost, which has favored offset. New, roll-fed inkjet printers are providing a meaningful alternative, and publishers now have a tinge of POD religion.

Major book printers offer digital and offset alternatives, and suppliers have many new systems for them. The economics of these new systems are changing the way we print books as well as the terminology we use.