Stressing the importance of nanotechnology in forthcoming technology, this analysis illustrates how the field bears great promise in forming the basis of future generations of electronic and optoelectronic devices. Discussing electrons and photons in and through nanostructures by the first-principles quantum mechanical theories and fundamental concepts behind nano-electronics and optoelectronics, the material basis, physical phenomena, device physics, designs, and applications, this crucial perspective combines a variety of expert viewpoints designed to foster further research?and to suggest the cross-disciplinary interaction required in surmounting the barriers facing future generations of technology design.