We review in these notes the recent results of the Pierre Auger Observatory related to ultra high energy cosmic rays. We describe the components of the observatory and the status of its operation. The observations related here cover the correlation with astrophysical sources and its implications, as well as the determination of the spectrum at the higher end of energy, and the detemination of the primary cosmic rays being photons. We also report on the limit of the neutrino flux. It is described the next steps in the layout of the Observatory, which includes extending the capabilities of the Southern observatory to lower energies and, in the Northen Hemisphere the construction of a new observatory in Colorado, USA.

We review in these notes the status of the construction of the Pierre Auger Observatory and present the first Physics results, based on the data collected during the first year and a half of operation. These results are preliminary, once the work to understand the systematics of the detectors are still underway. We discuss the cosmic ray spectrum above 3 EeV, based on the measurement done using the Surface Detector and the Fluorescence Detector, both, components of the observatory. We discuss, as well, the search for anisotropy near the Galactic Center and the limit on the photon fraction at the highest energies.

We review the status of ultrahigh energy cosmic rays studies, discussing the mechanisms for their production and propagation through space. We look into the strategy to measure those events and describe a new observatory, which is in construction, to observe those particles, the Pierre Auger Observatory.