A goal of plasmonics is to understand and manipulate surface plasmons at the nano-scale, so characterization of surface plasmons is important. Some techniques frequently used to characterize surface plasmons are dark-field microscopy, UV-vis-NIR spectroscopy, and surface-enhanced Raman scattering (SERS). With dark-field microscopy, it is possible to monitor the spectrum of an individual metal nanostructure as the incident light polarization, wavelength, or variations in the dielectric environment is changed.