Print on demand: You upload up your interior and cover files to one of the print on demand (POD) service companies. When a book is ordered, one copy is printed and sent directly to the customer. No paying upfront for print copies. No holding stock. No post office runs. You just get the profit after the sale. I highly recommend this option for most people as there is very little risk and you can buy a few of your own copies for giveaways, marketing and ego reasons. This is what I do and I'm very happy with it.