We have seen in this chapter that the FDTD method for solving Maxwell’s equations is accurate and versatile in a very wide variety of applications related to lightning. One can analyze the lightning electromagnetic field propagation over distances ranging from a few meters to hundreds of kilometers by just adjusting the smallest wavelength governed by the highest frequency of the band being simulated with the FDTD method. One can also take into account complex media in the EIWG by adding the media parameters through the simple discretization process. Moreover, a number of powerful software packages exist for FDTD modeling, including free, open-source packages and commercial program suites. One can also modify the basic codes to adapt them to any problem of interest. With the continued growth of computing resources, FDTD method will continue to serve as a helpful tool in research and engineering applications requiring lightning electromagnetic pulse (LEMP) simulations.