If the electronic book is ever to become a reality, there are countless technical hurdles to leap. One of the first problems, however, is to work out exactly what the end product should be. The author suggests that what is needed is an object that can be carried anywhere, and will allow the user to read any book in his/her collection wherever they are. This immediately places limits on size, weight and power requirements, and demands on the storage capacity of the `ebook'. These limiting factors are briefly discussed. The author then discusses the type of features such an ebook should have, with particular emphasis on the technical aspects from the user's and publisher's points of view.