The finite-difference time-domain (FDTD) method is one of the most widely adopted method for solving time-domain Maxwell’s equations due to its simplicity, flexibility for handling complex media, and explicit nature. However, in multiscale simulations, the permitted time-step size is restricted by the Courant-Friedrich-Levy (CFL) condition and thus unreasonably small due to the dense grid required for resolving fine geometry features, leading to prohibitive computational burden. This session focuses on the enhancement of the FDTD method for multiscale electromagnetic simulations, including yet not limited to efficient time integration methods, sub-cell modelling, subgridding methods, domain-decomposition techniques for the FDTD method, and hybrid algorithms of the FDTD method with other numerical methods.