"Unlike e-books, which also appeared in the late 1990's, P.O.D. self-publishing has developed into a real business, attracting involvement from the likes of Random House, Barnes & Noble and now Borders.

"We wanted to learn about the market," said Phil Ollila, Borders's vice president for book marketing, in explaining the chain's experiment. The company approached Xlibris, based in Philadelphia, one of the big three of P.O.D. self-publishing, together with 1stBooks and iUniverse, all formed in the late 1990's. Xlibris is 49 percent owned by Random House Ventures; 1stBooks, based in Bloomington, Ind., is privately held. Barnes & Noble owns 25 percent of iUniverse, based in Lincoln, Neb., and Warburg Pincus holds the other 75 percent.

The real challenge is not to produce books, it is to achieve all the goals of publishing - to get the books edited, distributed, noticed and, above all, bought. That is no easy feat: in the United States, 150,000-160,000 new titles were published last year, according to R.R. Bowker's Books in Print. On average, the P.O.D. titles sell just 150 to 175 copies, the companies say. Many authors are happy to pay for 50 or 100 copies of their magnum opus to give or sell to family, friends and business contacts. Others, though, confuse production with publication and end up disillusioned."