This article presents our comprehensive study in the new area of nanophotonics, which deals with optical processes at the nanoscale, much smaller than the wavelength of optical radiation. Nanoscale matter-radiation interactions, which include nanoscale confinement of radiation, nanoscale confinement of matter, and nanoscale photophysical or photochemical transformation, offer numerous opportunities for both fundamental research and technological applications. We present here selected examples of our studies in each of these areas. Nonlinear optical interactions involving nanoscale confinement of radiation are theoretically analyzed and experimentally probed using a near-field geometry. Nanoscale confined optical domains to control excitation dynamics and energy transfer and to produce photon localization are illustrated by examples of nanostructured rare-earth-doped glasses, multiphasic nanocomposites, and photonic band gap materials. One application of nanophotonics presented here is the utilization of spatially localized photochemistry using a near-field excitation for nanofabrication and nanoscale memory. The article concludes with a discussion of the future outlook for nanophotonics.