Liquid phase sintering (LPS) is a manufacturing process used to form high-performance, multi-phase components from powders. It involves sintering under conditions where solid grains coexist with a wetting liquid, leading to rapid densification and microstructure evolution. The process has been applied to a wide range of engineering materials, including automobile engine connecting rods and high-speed metal cutting inserts. Scientific advancements in understanding LPS began in the 1950s, and quantitative process models are now embedded in computer simulations to predict component dimensions, microstructure, and properties. The review, based on over 2,500 publications, focuses on the events that occur when mixed powders are heated to LPS temperatures, particularly the densification and microstructure evolution. Key aspects include the role of liquid formation, the influence of contact angles and dihedral angles on wetting and grain rearrangement, and the impact of solid-liquid solubility on the final microstructure. The review also discusses the evolution of microstructures, including grain size distribution, grain shape, and pore formation, and the relationships between microstructure and material properties. The microstructure of LPS materials is characterized by changes in porosity, grain size, and grain shape, which are influenced by factors such as liquid content, dihedral angle, and surface energy anisotropy. The review highlights the importance of controlling these parameters to optimize the final properties of the sintered components. Despite the challenges in modeling and controlling the microstructure, LPS remains a dominant commercial sintering process due to its ability to produce customized composite materials with tailored properties.Liquid phase sintering (LPS) is a manufacturing process used to form high-performance, multi-phase components from powders. It involves sintering under conditions where solid grains coexist with a wetting liquid, leading to rapid densification and microstructure evolution. The process has been applied to a wide range of engineering materials, including automobile engine connecting rods and high-speed metal cutting inserts. Scientific advancements in understanding LPS began in the 1950s, and quantitative process models are now embedded in computer simulations to predict component dimensions, microstructure, and properties. The review, based on over 2,500 publications, focuses on the events that occur when mixed powders are heated to LPS temperatures, particularly the densification and microstructure evolution. Key aspects include the role of liquid formation, the influence of contact angles and dihedral angles on wetting and grain rearrangement, and the impact of solid-liquid solubility on the final microstructure. The review also discusses the evolution of microstructures, including grain size distribution, grain shape, and pore formation, and the relationships between microstructure and material properties. The microstructure of LPS materials is characterized by changes in porosity, grain size, and grain shape, which are influenced by factors such as liquid content, dihedral angle, and surface energy anisotropy. The review highlights the importance of controlling these parameters to optimize the final properties of the sintered components. Despite the challenges in modeling and controlling the microstructure, LPS remains a dominant commercial sintering process due to its ability to produce customized composite materials with tailored properties.