OntoWeaver is an ontology-based approach, which provides high level support for web site design and development. It relies on the following major components to achieve its task: i) a site view ontology, which provides fine-grained modelling support for user interfaces and navigation structures of the target web site, ii) a presentation ontology, which provides high level support for the specification of layouts and presentation styles for user interface elements, and iii) a customization framework, which exploits the declarative specification of the target web site and provides comprehensive customization support at design time as well as run time.