This book has one purpose only: to enable the reader or student to learn how to do three- dimensional electromagnetic simulation using the finite-difference time-domain (FDTD) method It does not attempt to explain the theory of FDTD simulation in great detail. It is not a survey of all possible approaches to the FDTD method nor is it a "cookbook" of applications. It is aimed at those who would like to learn to do FDTD simulation in a reasonable amount of time.