Forward modeling is an important part of understanding controlled-source electromagnetic (CSEM) responses. The diffusive term in the electromagnetic wave equation is dominant over the displacement term at these frequencies. It is the diffusive behavior that makes it difficult to imagine the actual propagation of the signal. An important tool in gaining experience therefore is forward modeling, and lots of it. The advantage of one-dimensional (1D) forward modeling, besides its speed, is to study isolated effects (see for instance Key, 2009): What is the influence of resistivity anisotropy, or of fine-scale resistivity variations? What is the influence of the airwave? With 1D modeling you can quickly study these effects in isolation before you go on to more complex models in higher dimensions. For an introduction to CSEM for hydrocarbon exploration see, for instance, Constable (2010).