The Pierre Auger Observatory for the study of the Ultra-High Energy Cosmic Rays

The Pierre Auger Observatory is the world largest instrument for the observation of the high-energy cosmic rays. The installation of the Southern Observatory is now completed and, after only four years of data taking, the Auger collaboration has provided outstanding results regarding the origin of the most energetic cosmic rays. Results on energy spectrum, mass composition and anisotropy of the arrival directions are presented.