This paper discusses the genesis of e-books and derives a comprehensive definition from various definitions reported for them. It lists the various types of e-books with their characteristics and the major players in the market. It also highlights the pros and cons of e-books, and compares select e-book reader hardware and software with their specifications, requirements and characteristics. The impact of e-books on the publishing industry, on libraries and librarians, and digital rights management is discussed. The author concludes that e-books are rapidly becoming a viable alternative and provide growing advantages over the traditional medium.