Nano-Optics is the study of optical interactions, phenomena, and techniques on the sub-wavelength scale. In this presentation I will give an introduction into this emerging field of study and then focus on a new concept called "optical antenna". In optics, lenses and mirrors are used to redirect the wavefronts of propagating optical ra diation. But because of diffraction, propagating radiation cannot be localized to dimensions much smaller than the optical wavelength. Borrowing concepts developed in the radiowave and microwave regime, we use antennas to localize optical radiation to length-scales much smaller than the wavelength of light. We place a laser-irradiated optical antenna, such as a bare metal tip, a few nanometers above a sample surface in order to establish a localized optical interaction and a spectroscopic response (fluorescence, absorption, Raman scattering, ... ). This type of near-field optical spectroscopy has been applied to map out phonons in individual single-walled carbon nanotubes (SWNT) with a resolution of 10nm. The proximity of the antenna influences the local light-matter interaction and affects the selection rules, the quantum yield, and momentum conservation. Using the fluorescence from a single molecule we are investigating these effects and we characterized the trade-off between fluorescence enhancement and fluorescence quenching.