  I present a brief introduction to the lattice formulation of quantum field
theory, and discuss the use of lattice simulations for studies in particle
physics phenomenology. The computation of $f_B$, the decay constant of the
$B$-meson, is used as a case study. I also explain the appearance and
cancellation of ``renormalons'' in the evaluation of power corrections
(higher-twist corrections) in hard scattering and decay processes.
