The valence band is a term used in solid-state physics to describe the highest energy band of electrons in a material that are involved in bonding with neighboring atoms. It is located just below the conduction band in the energy band structure of a material. The electrons in the valence band are typically responsible for many of the material's properties, including its electrical conductivity and optical properties. Understanding the behavior of electrons in the valence band is crucial for designing and creating new materials with specific properties for various applications in electronics, optics, and other fields.