Ultrathin magnetic films have been studied and used in low-dimensional systems and materials employed32 in spintronics. In these systems, the interfaces play a crucial role. The magnetic properties of interface atoms are different from those in the bulk. First-principle calculations indicate that the bulk properties are almost fully acquired just a few atomic layers from the interface. Ultrathin films behave like giant magnetic molecules having their magnetic properties given by an admixture of the interface and bulk properties. The ability to admix the interface and bulk magnetic properties and combine the magnetic films together by nonmagnetic interlayers allows one to engineer unique magnetic materials. In the following three sections, the emphases 33will be put on the basic magnetic properties: magnetic anisotropy, exchange coupling, and exchange bias (EB) coupling. Each section starts with a general theoretical introduction, followed by most common experimental techniques, and a brief summary of important experimental studies, which played a crucial role in the development of magnetic nanostructures. We apologize to those who feel that their work and contributions were either insufficiently covered or perhaps even omitted. This is certainly not intentional. The goal of these sections is not to provide a comprehensive account of this field. The page limitation allows one to provide only basic ideas that are needed for specialists and graduate students entering the field of magnetic nanostructures and spintronics applications. There are many references in this chapter to important books and review articles where further details and references can be found.