A psychrometric chart is a graphical representation of the physical and thermal properties of moist air. It displays various parameters such as temperature, humidity, and enthalpy, allowing users to analyze air conditions easily. The chart helps engineers and HVAC professionals design systems for heating, ventilation, and air conditioning by visualizing how air properties change with different conditions. The chart consists of curved lines representing relative humidity, dry bulb temperature, and wet bulb temperature. By plotting points on the chart, users can determine the moisture content and energy levels of air, facilitating better decision-making in climate control and comfort applications.