Computing at the Petabyte scale with the WLCG

The Worldwide LHC Computing Grid provides and operates the Grid infrastructure used by the experiments of the Large Hadron Collider at CERN for their data processing. The huge amount of data to be distributed and analysed, the number of collaborating centres and users and the diversity of the underlying resources make the WLCG the largest and most complex research Grid currently in operation. In this paper we describe how the WLCG successfully provides a scalable system for the LHC experiments and its recent successes during data challenges and data taking