 Coupling combined with the chemical shift (and the integration for protons) tells us not only about the chemical environment of the nuclei, but also the number of "neighboring" NMR active nuclei within the molecule.In more complex spectra with multiple peaks at similar chemical shifts or in spectra of nuclei other than hydrogen, coupling is often the only way to distinguish different nuclei.The above description assumes that the coupling constant is small in comparison with the difference in NMR frequencies between the inequivalent spins.