Online retailer Amazon claims that, in the UK, its e-book sales have raced past its hardback and paperback sales.
Amazon's Kindle, which uses e-ink, has proved wildly popular since its 2010 launch and offers the benefits of convenience for content delivery, cutting down on physical storage, and its lightweight design.
We would speculate that the tipping point for beating hard copy sales is the nature of the Kindle - that buying books is made easy, meaning users can queue up a significant amount of content, perhaps more than they can realistically read.
However, for authors self-publishing, the Kindle and the e-book market, through Amazon, has been a boon. One writer told TechEye that, although there were difficulties in reformatting for the device, the Kindle offers an advantage and the margins are better.
"Mostly it is because distribution costs are tiny," the author said. "In a paperback you lose 60 percent to distribution".
What, then, about the dubious glory of giving the world 50 Shades of Grey? "That is one of the advantages of the e-book market," our source said. "Publishers would not have thought that the cougar market would earn them big bucks before."
Amazon's Kindle has faced competition from Barnes & Noble's Nook, the Kobo reader, and from elsewhere. The iPad could be considered competition, but it seems that Amazon's model for a lightweight, relatively cheap, e-ink device is keeping it way ahead of the digital reading market.
The traditional publisher is far from dead so far - rather than replacing hard copies, the Kindle can complement them - but, as the MP3 transformed the music industry, the success of the e-book does suggest a transformative period is underway in the realm of publishing.