After an introduction into diffusive shock acceleration, I discuss recent
prospects in theory and observations,
in particular the idea of magnetic
 field amplification by cosmic rays. Then I review the (controversial) status
of the transition to extragalactic cosmic rays and the chemical composition
at the highest energies. The prospects
of identify the source of ultrahigh
energy cosmic rays depends crucially on the later and the strength of
 magnetic
fields and I discuss strategies to distinguish sources classes.