  Many results from lattice QCD of broad importance to particle and nuclear
physics are obtained with 2+1 flavors of staggered sea quarks. In the continuum
limit, staggered fermions yield four species, called tastes. To reduce the
number of tastes to one (per flavor), the simulation employs the fourth root of
the four-taste staggered fermion determinant. This talk surveys evidence in
favor of this procedure, refutes recent criticisms, and reviews recent
algorithmic and technical improvements. Physics results are covered in other
plenary talks.
