An e-book also called eBook, ebook, electronic book, is an electronic (or digital) equivalent of a conventional printed book and is a proprietary file formats. Some e-books are produced simultaneously with the production of a printed book, though in many instances they may not be put on sale until later. Often, e-books are produced from pre-existing hard-copy books, generally by document scanning, sometimes with the use of Robotic Scanners, having the technology to quickly scan books without damaging the original print edition. Scanning a book produces an image file, which must then be converted into text format by an Optical Character Recognition (OCR) program. Occasionally, an e-book may also be produced by re-entering the text from a keyboard. As a newer development, sometimes only the e-book form is produced by the publisher; it is usually possible technically to convert this to a printed book by short-run printing.

A writer or publisher has many options when it comes to choosing a format for production of e-book. Formats available include, but are by no means limited to image file (.png, .jpg), Microsoft Word or plain text files (.doc or .txt), Rich Text Format (.rtf), Hyper Text Markup Language (HTML) (.html), Open Electronic Book Package Format (OPF), Portable Document Format (.pdf), etc.

The hardware device used to read books in digital format is known as an e-book device or e-book reader. The e-book reader includes FlipViewer®, Haali Reader and FBReader, Plucker, Acrobat Reader or Adobe Reader, Mobipocket (.prc), Cybook (Bookeen), iRex iLiad (based on eInk), Sony Reader (based on eInk), eBookwise-1150 (based on former Gemstar technology), Jinke Hanlin Reader (based on eInk), DNL Reader eReader (formerly Palm Digital Media) (.pdb), etc.

Among the first Internet-only publishers of new e-books were Boson Books, Hard Shell Word Factory and Online Originals, all founded in the mid-1990s. Online Originals was the first e-book publisher to win mainstream book reviews (in the London Times) and a nomination for a major literary prize (the Booker Prize).

Since the late 1990s, the many newcomers to e-book publishing have included most major print publishers. At the same time, many established e-publishers started to offer print versions of some of their titles. Thus the line between the two is fast blurring.