Cosmic Particles at Extreme Energies

Cosmic rays are the highest energy messengers of astrophysical phenomena in the Universe. The sources of these particles are unknown and it is one of the great puzzles of modern astrophysics how they are accelerated to macroscopic energies of $>10^{20}$ eV. In this talk I will highlight recent experimental results on ultrahigh-energy cosmic rays and discuss their implications on our understanding of the physics and astrophysics at extreme energies.