Electronic versions of textbooks (e-textbooks) have recently become a hot topic in the educational community. A good e-textbook should be quite different from a printed textbook. It should provide much more besides the obvious additions and improvements such as interactivity, multimedia, and ease of navigation. As the need for individual approach towards each student is becoming more and more accentuated, one of the crucial changes that are expected is that an e-textbook should allow for customisation and personalization. Customisation will be one of the most important parts of the teachers' duties in the future. Teachers are the ones capable of making the proper combination of resources, making it suitable for a particular pedagogical situation. Therefore, e-textbooks should be designed to be adaptable to the pedagogical situation and to the user, be it a learner or a teacher. Consequently, e-textbooks must be different from the printed editions. It should be a given that an e-textbook allows for and enables uncomplicated customization and personalisation.