In the past decade the number of ultra-high energy cosmic rays detected has increased enormously. This is mostly due to the operation of the Pierre Auger Observatory, in Argentina, the largest cosmic ray detector ever built. Through this detector we now know better the most energetic particles in the universe, we can now start to answer some of the most important questions, such as where do they come from? What are they? How do they interact with the atmosphere? In this proceedings a selection of the most important results of Auger are presented, with particular focus on those of astrophysical interest.