This book intends to be an easy and concise introduction to the field of nuclear magnetic resonance, or NMR, which has revolutionized life sciences in the last twenty years. A significant part of the progress observed in scientific areas like chemistry, biology, or medicine can be ascribed to the development experienced by NMR in recent times. Many of the books currently available on NMR deal with the theoretical basis and some of its main applications, but they generally demand a strong background in physics and mathematics for a full understanding. This book is aimed at a wide scientific audience, trying to introduce NMR by making all possible effort to remove, without losing any formality and rigor, most of the theoretical jargon that is present in other NMR books. Furthermore, illustrations are provided that show all the basic concepts using a naive vector formalism.