The goal of the present document is to provide a concept for addressing quality of experience. This concept concerns the following aspects: ? A clear and unambiguous terminology concerning concepts (services@ quality@ Qoe@ etc.) as they should be used to address quality of experience. ? A theoretical and abstract model for QoE: the ARCU model. ? An operational and generic abstraction for modelling and estimating QoE: the QoE layered model. ? The specification of a software agent implementing the QoE layered model.