  One of the most striking astrophysical phenomena today is the existence of
cosmic ray particles with energies in excess of 10^20 eV. While their presence
has been confirmed by a number of experiments, it is not clear where and how
these particles are accelerated to these energies and how they travel
astronomical distances without substantial energy loss. We are entering an
exciting new era in cosmic ray physics, with instruments now producing data of
unprecedented quality and quantity to tackle the many open questions. This
paper reviews the current experimental status of cosmic ray physics and
summarizes recent results on the energy spectrum and arrival directions of
ultra-high-energy cosmic rays.
