Stokes and Anti-Stokes lines refer to the spectral lines observed in Raman scattering, where Stokes lines are shifted to longer wavelengths due to energy transfer from the photon to the material, while Anti-Stokes lines are shifted to shorter wavelengths as the photon gains energy from the material. These shifts provide crucial insights into the vibrational and rotational modes of molecules, aiding in material characterization and molecular analysis.