This presentation highlights of some scientific insights on the possibilities of photonic applications of silicon nanostructures (NSs) one of the most fertile research field in nano-crystallite physics that has innumerable possibilities of device applications. Nanostructured silicon is generic name used for porous Si (p-Si) as well as Si nanocrystals (NC-Si) having length scale of the order of few nanometer. The emission of a very bright photo-luminescence (PL) band and relatively weak electro-luminescence (EL) from low-dimensional silicon has opened up new avenue in recent years. It is important from a fundamental physics viewpoint because of the potential application of Si wires and dots in opto-electronics devices and information technology. Nanostructuring silicon is an effective way to turn silicon into a photonic material. It is observed that low-dimensional (one and two dimensions) silicon shows light amplification, photon confinement, photon trapping as well as non-linear optical effects. There is strong evidence of light localization and gas sensing properties of such NSs. Future nano-technology would replace electrical with optical interconnects that has appealing potentialities for higher-speed performance and immunity to signal cross talk. A varieties of applications includes LD, LED, solar cells, sensors, photonic band gap devices and Fibonacci quasi-crystals, to cite a few.