Digital publishing is a growing market, currently estimated to account for 5-10% of some large publishers' revenue but forecasted to reach 25% of book sales by 2015. While ebooks are currently simple digital versions of print books, enhanced ebooks and apps allow for additional features like video, audio, and interactivity. Producing digital products requires reformatting content and can cost from £50-£20,000 depending on features. Publishers are experimenting with digital formats for the Christmas market and see opportunities in marketing titles through apps and ebooks, though success will require an innovative approach.