  This paper presents the highlights from the recent measurements of the energy
spectrum, mass composition, and arrival directions of the ultra-high energy ($>
10^{17}$ eV = 0.1 EeV) cosmic rays (UHECR) by the Pierre Auger Observatory. The
Auger hybrid detector combines fluorescence observations of the longitudinal
profiles of extended air showers, initiated by these extremely energetic
particles, with measures of the shower secondaries at the ground level by its
large array of Cherenkov water tanks. The complementariness of the two
techniques provides important cross-checks at the energies unreachable with
accelerator experiments. The Pierre Auger experiment has observed a strong
steepening of the cosmic ray flux above 40 EeV. A significant anisotropy in the
arrival directions of cosmic rays has been established for events above $\simeq
60$ EeV. These events correlate over angular scales of less than 6$^\circ$ with
the directions towards nearby ($D < 100$ Mpc) active galactic nuclei. Both
observations are consistent with the standard scenarios of the UHECR production
in the extragalactic astrophysical acceleration sites. The derived stringent
upper limits on the photon and neutrino contents in the UHECR are additional
important arguments in support of these scenarios. The measurements of the
variation of the depth of shower maximum with energy, interpreted with the
current hadronic interaction models, favour the mixed cosmic ray composition at
energies above 0.4 EeV. We describe the plans and prospects for the future,
that will further help to solve the 50 years old UHECR puzzle.
