In the context of the Semantic Web, notions of collaboration, interoperability, and reuse are intrinsically interrelated: interoperability implies reuse, which in turn can be seen as a form of collaboration. In this context, as we move from classic Web 2.0 to scenarios in which semantic content is central, our technologies need to change so that it becomes possible to create and exchange knowledge transparently, consistently with the openness of the Web. In this article, the authors examine different modalities for collaborative semantic authoring on the Web. To this purpose, they present three novel tools that correspond to different levels of interaction between the user and the created resources, as well as different levels of interoperation between various resources on the Semantic Web.