  It is argued that there are three `origins' of cosmic rays; the origin of the
particles, the origin of the energy, and the site of the acceleration. The
evidence for each origin is discussed and a plausible synthesis outlined for
the particles of Galactic origin where the energy comes mainly (but not
exclusively) from supernova explosions, the site of the acceleration is at
strong collisionless shock waves, and the accelerated particles come from the
interstellar and circumstellar material swept over by these shocks. If these
shocks are capable (as indicated by recent observations and theoretical work)
of significantly amplifying magnetic fields this picture appears capable of
explaining the cosmic ray particles at all energies below the `ankle' at
$3\times10^{18}\,\rm eV$. The particles above this energy are generally taken
to be of extra-galactic origin and possible acceleration sites for these UHE
particles are briefly discussed.
