Surface plasmon resonance (SPR) is a powerful analytical technique widely used in the field of biosensors and material science. It involves the excitation of surface plasmons, collective oscillations of free electrons at the interface between a metal and a dielectric medium, using polarized light. When molecules bind to the metal surface, it changes the refractive index near the surface, leading to a shift in the resonance angle or wavelength of the reflected light. This shift can be monitored in real-time to quantify binding events between biomolecules, such as proteins and DNA, and analyze interactions in complex biological systems. SPR is a label-free and highly sensitive technique, making it a valuable tool for studying molecular interactions, drug discovery, and medical diagnostics.