Reservoir modeling is a vital step in the development and production of oil and gas fields. An accurate three-dimensional reservoir model reduces the uncertainties and drilling risks and leads to a more realistic productive forecast. To this end, prediction of reservoir�s structural framework together with reservoir properties (rock and fluid) are regarded as crucial steps in reservoir simulation models. To generate such a numerical reservoir model, petrophysical properties such as mineral volume, porosity, fluid saturation, and pressure are traditionally distributed between the wells using geostatistical techniques. Incorporating only well data, geological facies, and petrophysical information may not be sufficient for disclosing anomalous zone, particularly in the presence of lithofacies changes. Although well logs and core data possess high vertical resolution, interpolation solely based on sparse well data is not geologically consistent because of nonuniform lateral variation of reservoir properties, for example, porosity and permeability. To overcome this issue, seismic data, as a laterally extended data, is widely used in a seismic reservoir characterization scheme. However, seismic data has some inherent limitations, such as anisotropic effect, vertical resolution, and nonuniqueness in converting seismic data to reservoir properties. In this chapter, first the basic concepts and fundamental principles of reservoir modeling are explained. Next, the required steps to build static and dynamic reservoir models are elaborated. The application of four-dimensional seismic monitoring in reservoir surveillance is discussed. Drilling optimization and economic evaluation are briefly presented. The last section discusses the complementary aspects of reservoir modeling. © 2022 Elsevier Inc. All rights reserved.