PERIMETER's main objective is to establish a new paradigm of user-centricity for advanced networking. In contrast to network-centric approaches, user-centric strategies could achieve true seamless mobility. Putting the user at the centre rather than the operator enables the user to control his or her identity, preferences and credentials, and so seamless mobility is streamlined, enabling mobile users to be "Always Best Connected" in multiple-access multiple-operator networks of the Future Internet.For that, PERIMETER will develop and implement protocols designed to cope with increased scale, complexity, mobility and requirements for privacy, security, resilience and transparency of the Future Internet. These include appropriate mechanisms for network selection based on Quality of Experience; innovative implementation of "Distributed A3M" protocols for Fast Authentication, Authorisation and Accounting based on privacy-preserving digital identity models. All these mechanisms will be designed to be independent from the underlying networking technology and service provider, so that fast, inter-technology handovers will be possible.PERIMETER will also develop and implement middleware that support generic Quality of Experience models, signalling and content adaptation, and exemplary extension applications and services for user-centric seamless mobility.The paradigms of user-centric seamless mobility, middleware components and its integrated applications and services will be tested in two large-scale interconnected testbeds on real users, in three cycles of increasingly complex scenarios. The results will be used for assessment of user centricity.The realization of user-centric paradigm will revolutionise mobile communications. It will impact seamless mobility, issues of security and privacy, standards and future research, and it will maintain Europe's leading position in the race to define and develop the network and service infrastructures of the Future Internet.