World Wide Web software development is a challenge. The need to provide appealing and attractive user interfaces is combined with the fact that the World Wide Web is not merely an information transfer tool anymore. The capacity to offer additional services plays an important role. The World Wide Web makes these services available to a greater number of individuals who have different characteristics, knowledge and profiles. The World Wide Web demands quick development with high quality level. This chapter makes an important contribution in the field of software product characterization for the World Wide Web, proposing a quality model that focuses on quality in use or usability. Said quality model, which has been partially tested on real users through several experiments, is based on international standards and ergonomic criteria. The model has proved useful for organizing and applying the experience available in the development of user interfaces for Web applications and has improved noticeably its final quality in use. INFORMATION SCIENCE PUBLISHING IGR5159