Psychrometry is the study of the physical and thermodynamic properties of air-vapor mixtures, particularly in relation to human comfort, heating, ventilation, and air conditioning (HVAC) systems. It involves the measurement and analysis of air properties such as temperature, humidity, enthalpy, and specific volume. Psychrometry is crucial in understanding and designing systems that control indoor air quality and thermal comfort. By applying psychrometric principles, engineers can determine the properties of air at various conditions, predict the effects of heating, cooling, humidification, and dehumidification processes, and design systems that provide optimal indoor environments. Psychrometric charts and tables are essential tools used to visualize and calculate the properties of air-vapor mixtures, enabling the development of efficient and effective HVAC systems that meet the needs of building occupants. By understanding psychrometry, professionals can create indoor environments that are comfortable, healthy, and sustainable.