Chemical Shift refers to the change in the resonance frequency of a nucleus in a magnetic field due to its electronic environment. This phenomenon is crucial in techniques like Nuclear Magnetic Resonance (NMR) spectroscopy, where it helps identify different chemical environments of atoms in a molecule. The chemical shift is measured in parts per million (ppm) and provides insights into molecular structure and dynamics. Variations in chemical shifts occur because nearby atoms and functional groups influence the magnetic field experienced by the nucleus, allowing chemists to deduce information about molecular interactions and arrangements.