This presentation was delivered during the joint DPE/Planets/CAPAR/nestor training event, ‘The Preservation challenge: basic concepts and practical applications’ (Barcelona, March 2009). It explains how CASPAR aims to solve, from the technical point of view, the problem of accessibility and intelligibility of digital data in the long term.CASPAR approach is presented as an implementation of the OAIS functional model, introducing CASPAR Key Components, i.e. the main building blocks which constitute CASPAR architecture, and giving an overview of their functionalities, their usage and their role in the digital preservation workflow. The objective is to clarify how the digital preservation workflow is realised within CASPAR architecture.