 Current FDTD modeling applications range from near-DC (ultralow-frequency geophysics involving the entire Earth-ionosphere waveguide) through microwaves (radar signature technology, antennas, wireless communications devices, digital interconnects, biomedical imaging/treatment) to visible light (photonic crystals, nanoplasmonics, solitons, microscopy and lithography, and biophotonics).At least 28 commercial FDTD software suites and 16 free-software/open-source or closed-source FDTD projects are available.To a large degree, all of these software constructs derive directly from FDTD techniques first reported by Prof. Taflove and his students over the past 45 years.