Elaborating on the function of mass-market paperbacks in this day and age. The wholesale market is/was a notoriously inefficient way of selling books; you'd sometimes have to ship two books to sell one, with the unsold one ending up stripped and pulped on a conveyor belt somewhere. I once visited a wholesale distribution center in Florida and witnessed sights no reader or writer should ever see: entire assembly lines devoted to stripping and pulping unsold paperbacks. It was the abattoir of authors' dreams. BUT . . . one of the big reasons for still selling books that way was because, in theory, that's how you hooked new readers, and got them into the habit of reading. Bookstores are great, but they're mostly frequented by people who already love books. The drugstores and grocery store racks were where you went to get the impulse buyers -- and hopefully turn them into the sort of people who frequent bookstores. Or at least that was the idea back before ebooks and the internet.