A hygrometer is the instrument used to measure humidity. It assesses the amount of water vapor present in the air, which is expressed as relative humidity percentage. Various types of hygrometers exist, including analog and digital devices, as well as mechanical options like hair hygrometers and electronic sensors. Accurate humidity measurement is crucial in various fields, such as meteorology, agriculture, and building maintenance, as humidity levels significantly influence weather patterns, plant growth, and the durability of materials. Monitoring humidity is vital for maintaining comfort and safety in indoor environments like homes and workplaces.