This book offers a multimodal social semiotic perspective on the ways in which websites as hypermedia texts mediate and construct knowledge in mass media and education contexts. Specifically, the book proposes new tools for analysing how websites construe meanings through the interation of visual, verbal, kinetic and aural resources (i.e. multimodally and multimedially) and hyperlinks (i.e. hypertextually). To introduce the tools and demonstrate their value for research in applied linguistics, discourse analysis, media/communication studies, and education, the book presents analyses of websites for children, online news websites, and of users' navigation paths through some of these hypermedia texts. The selected Web texts epitomise the three key challenges that hypermedia texts on the Web present for discourse analysis: the interaction of multimodality and hypertextuality, the fluidity of hypermedia texts, and their generic hybridity.