Full-wave numerical electromagnetic analysis (NEA) methods are defined as methodologies allowing the direct numerical solution of Maxwell's equations in both frequency and time domain. These methods are becoming the most promising approach to study complex transient phenomena that cannot be straightforwardly solved by means of circuit-theory or transmission line approaches (e.g. by using Electromagnetic Transient Program - EMTP). Indeed, as known, circuit-theory/transmission line based approaches cannot solve transients that involve non-TEM propagation modes. Furthermore, they cannot be applied in case of unknown circuit parameters. Within the context of NEA, this paper describes the basic theory of the finite-difference time-domain (FDTD) method as a representative NEA method. Also, some typical examples are presented to demonstrate its usefulness and advantages. © 2011 IEEE.