Condensation, a vapor-to-liquid phase change process, plays an essential role in energy conservation, environmental processes, and the recovery of water. It exists in two forms: filmwise and dropwise condensation. The presence of non-condensable gases impacts condensation differently than that of pure water vapor. Consequently, a comprehensive understanding of pure water vapor and its condensation within moist air emerges as a pivotal area of research. In filmwise condensation, a continuous liquid film presents high thermal resistance and diminished heat transfer efficiency. In contrast, dropwise condensation, which is facilitated by non-wetting surfaces, generates discrete droplets that continually renew the surface, thus significantly enhancing the heat transfer coefficient. Various surface characteristics, including wettability, roughness, subcooling, and chemical composition, determine the transition between these modes. This chapter elucidates the mechanisms underlying both filmwise and dropwise condensation, introduces a mathematical model for each process, reviews recent advancements in engineered surfaces for condensation, and examines the optimization of various parameters related to pure vapor and moist air condensation. Furthermore, it is suggested that cooling the surface to create conducive conditions for atmospheric water condensation is a viable approach. The promotion of stable dropwise condensation of water vapor in moist air is deemed essential for achieving efficient atmospheric water harvesting. Hydrophobic and superhydrophobic coatings substantially enhance dropwise condensation by incorporating micro/nanostructures and utilizing low surface energy materials. This area of research is critical for the successful implementation of efficient atmospheric water harvesting technologies. Condensation, a vapor-to-liquid phase change,is vital for energy conservation, environmental processes, and clean waterrecovery. It occurs as filmwise and dropwise modes. Non-condensable gasesaffect these processes differently, making understanding vapor condensation inmoist air crucial. Filmwise involves high thermal resistance due to acontinuous liquid film, while dropwise, enabled by non-wetting surfaces, formsdroplets that enhance heat transfer. Surface features like wettability,roughness, subcooling, and chemistry influence these modes. This chapter coversmechanisms, models, recent surface innovations, and parameter optimization forcondensation. Condensing surfaces to promote atmospheric water condensation arepromising. Stable dropwise condensation is key for water harvesting, improvedby hydrophobic and superhydrophobic coatings with micro and nanostructures andlow energy materials.