This chapter at first surveys the Web technologies that can enable ubiquitous and pervasive multimedia communications over the Web and then reviews the challenges that are raised by their combination. In this context, the relevant HTML5 APIs and technologies provided for service adaptation are introduced and the MPEG-DASH, X3Dom, and WebRTC frameworks are discussed. What is envisaged for the future of mobile multimedia is that with the integration of these technologies one can shape a diversity of future pervasive and personalized cloud-based Web applications, where the client-server operations are obsolete. In particular, it is believed that in the future Web cloud-based Web applications will be able to communicate, stream, and transfer adaptive events and content to their clients, creating a fully collaborative and pervasive Web 3D environment.