  We investigate the properties of staggered-fermion lattice QCD in which the
fourth root of the fermion determinant is taken. We show that this theory is
non-local at non-zero lattice spacing $a$, and that the non-locality is caused
by the breaking of taste symmetry at $a\ne 0$. We then present a
renormalization-group based argument that the theory restores taste symmetry in
the continuum limit. As a consequence the theory is local in that limit, and
falls into the correct universality class. Finally, we argue that the correct
effective theory for the physics of Goldstone bosons at $a\ne 0$ is given by
staggered chiral perturbation theory with the replica trick.
