Nano-optics is a branch of optics which studies and manipulates light at the nanometer scale. It involves the characterization and manipulation of light at the nanoscale, including the use of nanoscale optical components and structures, as well as the development of nanoscale optical devices. Nano-optics can be used to study and control light propagation on the nanoscale, from the interaction of light with individual molecules or nanoparticles to light propagation in complex nanostructured materials.