Plasmonic nanostructures are tiny metallic structures, often made from materials like gold or silver, that can manipulate light at the nanoscale. They exploit the phenomenon of surface plasmon resonance, where free electrons on the metal's surface oscillate in response to light, enhancing electromagnetic fields. This property allows them to interact with light in unique ways, making them useful in various applications. These nanostructures are used in fields such as sensing, imaging, and photovoltaics. By concentrating light into small volumes, they can improve the efficiency of solar cells and enhance the sensitivity of biosensors, leading to advancements in technology and medicine.