Book excerpt: Because of unique water properties, humidity affects many living organisms, including humans and materials. Humidity control is important in various fields, from production management to creating a comfortable living environment. The second volume of The Handbook of Humidity Measurement is entirely devoted to the consideration of different types of solid-state devices developed for humidity measurement. This volume discusses the advantages and disadvantages about the capacitive, resistive, gravimetric, hygrometric, field ionization, microwave, Schottky barrier, Kelvin probe, field-effect transistor, solid-state electrochemical, and thermal conductivity-based humidity sensors. Additional features include: Provides a comprehensive analysis of the properties of humidity-sensitive materials, used for the development of such devices. Describes numerous strategies for the fabrication and characterization of humidity sensitive materials and sensing structures used in sensor applications. Explores new approaches proposed for the development of humidity sensors. Considers conventional devices such as phsychometers, gravimetric, mechanical (hair), electrolytic, child mirror hygrometers, etc., which were used for the measurement of humidity for several centuries. Handbook of Humidity Measurement, Volume 2: Electronic and Electrical Humidity Sensors provides valuable information for practicing engineers, measurement experts, laboratory technicians, project managers in industries and national laboratories, as well as university students and professors interested in solutions to humidity measurement tasks as well as in understanding fundamentals of any gas sensor operation and development.