Within economics a relatively new way of modeling has dominated important subfields: structural modeling. The goal of this book is to give an overview on how the various streams of literatures in empirical industrial organization and quantitative marketing use structural econometric modeling to estimate the model parameters, give the economic-model-based predictions, and conduct the policy counterfactual experiments. The traditional way of modelling, called "reduced-form" builds its models from simple relationships between variables of interests, which are mostly linear.