Surface-enhanced Raman spectroscopy (SERS) is a sensitive analytical technique that enhances the Raman scattering of molecules adsorbed on rough metal surfaces or nanoparticles. This enhancement allows for the detection of low concentrations of substances, making it valuable in fields like chemistry, biology, and environmental science. The technique works by using noble metals such as silver or gold, which create localized electromagnetic fields when illuminated by a laser. These fields amplify the Raman signal, enabling researchers to obtain detailed information about molecular vibrations and chemical compositions, even at the single-molecule level.