The Webdam ERC grant is a five-year project that started in December 2008. The goal is to develop a formal model for Web data management that would open new horizons for the development of the Web in a well-principled way, enhancing its functionality, performance, and reliability. Specifically, the goal is to develop a universally accepted formal frame- work for describing complex and flexible interacting Web applications featuring notably data exchange, sharing, inte- gration, querying, and updating. We also propose to develop formal foundations that will enable peers to concurrently reason about global data management activities, cooperate in solving specific tasks, and support services with desired qual- ity of service. Although the proposal addresses fundamental issues, its goal is to serve as the basis for future software development for Web data management.