Surface plasmonics polaritons are waves that propagate along the metal-dielectric interfaces, caused by the collective oscillations of electron plasma in the metal induced by the external electromagnetic field. With the properties of sub-wavelength localization, near-field enhacement and novel dispertions, surface plamon polaritons play a significant role in nanophotonics. Plasmonic devices have the potential of integrating microelectronics and photonics in one chip beyond the diffraction limit. The basic principles of plasmonics, and their applications in optical waveguides, detectors, modulators and solar cells are discussed.