Proton NMR is without a doubt the single most important spectroscopic technique for organic chemists who are attempting to determine or confirm the identity of a compound. I want to emphasize here that the theory and uses of NMR are very complex. There are dozens if not hundreds of NMR experiments that can be performed besides the carbon and proton NMR experiments that are familiar to you from your undergrad organic course. If you want to learn more about the theory behind NMR and the myriad ways it can be used, you can look into taking an NMR class at your university. How NMR Works (In a Nutshell) You are hopefully familiar with the fact that electrons have spins from general chemistry. Recall that these spins can be up or down, that a given electron''''s spin is represented by the quantum number ms, and that ms has two possible values of +1/2 and -1/2. This is only part of the spin story in atoms, however. It turns out that certain isotopes of certain elements, including hydrogen-1 (protons) and carbon-13, have nuclear spins as well. Note that carbon-12, the most common isotope of carbon, does NOT have a nuclear spin, and therefore carbon-12 CANNOT undergo NMR.