**Abstract**

Nanophotonics encompasses a wide range of nontrivial physical effects including light-matter interactions that are well beyond diffraction limits, and have opened up new avenues for a variety of applications in light harvesting, sensing, luminescence, optical switching, and media transmitting technologies. Recently, growing expertise of fusing nanotechnology and photonics has become fundamental, arising outskirts, challenging basic experimentation and opportunities for new technologies in our daily lives, and played a central role in many optical systems. It entails the theoretical study of photon's interactions with matter at incredibly small scales, known as nanostructures, in order to prepare nanometer scale devices and accessories for processing, development, slowing down, influencing, and/or regulating photons through comprehending their behavior while interacting with or otherwise traveling via matter. This multidisciplinary field has also made an impact on industry, allowing researchers to explore new horizons in design, applied science, physical science, chemistry, materials science, and biomedical technologies. The foundations, nano-confinements, quantum manifestations, nanoscale interactions, numerical methods, and peculiarities of nonlinear optical phenomena in nano-photonics as well as projected nano-photonics consumption's in our cutting-edge world, will be covered in this chapter.

**Keywords:** nanophotonics, foundations, nano-confinements, quantum confinements, optical interactions, numerical simulations, nonlinear optical phenomena
