This book investigates the use of static, adaptive, adaptable and mixed-initiative approaches to the personalisation of web content and graphical user interfaces (GUIs). This empirical study consisted of three experimental phases. The first examined the use of static, adaptive, adaptable and mixed- initiative approaches to web content. More specifically, it measured the usability (efficiency, frequency of error occurrence, effectiveness and satisfaction) of an e- commerce website. The second experiment examined the use of adaptive, adaptable and mixed-initiative approaches to GUIs. More...