The microstructure has an extreme impact on the durability of concrete. Many researchers focus on this area to understand the impact of microstructure on concrete durability. This review article discusses the microstructure present in the concrete such as porosity, permeability, and other factors that affect the durability of concrete. In addition, methods used in the durability test such as Mercury intrusion porosimetry, Nitrogen adsorption method, X-ray micro tomography, Sulphate attack, Half-Cell Potentials, and Rapid chloride permeability are also described. The overall analysis in this field shows that porosity and permeability are the main factors influencing the durability of cementitious materials. However, with enough hydration, porosity can be minimized to a certain extent. The permeability of cementitious material largely depends on several factors including sample preparation, curing conditions, type of media, and age of the sample. Water continuity, sulfate chloride attack, carbonation, and the alkali-aggregate reaction are extrinsic factors that affect concrete's durability. This review also discusses emerging research areas such as admixtures and sensors that are involved in health monitoring of concrete.