In this book the author will present several approaches for modelling and identification of seismic records based on formulations for source and transmission path. This will demonstrate an approach based on a criterion other that statistical goodness of fit. They will provide reasons for the success of the models and methods that are used frequently. This will provide a criterion to decide which models are good for all data sets, not just for the data at hand. Moreover, we will explain the relationships that exist between certain geophysical variables (e.g. corner frequency) and statistical quantities (e.g. zero-crossing) and use that to support our modelling and identification approaches.