Heterostructures are materials made by stacking different layers of semiconductors or other materials, each with distinct properties. This layering allows for unique electronic and optical behaviors that are not found in single materials. Heterostructures are essential in modern electronics, enabling the development of devices like lasers and transistors. These structures can be engineered to create specific band gaps, which are energy ranges that electrons cannot occupy. By carefully choosing the materials and their thicknesses, scientists can tailor the performance of devices for applications in photovoltaics, quantum computing, and LED technology.