Quantum wells, quantum wires, quantum dots. These are terms that have become familiar not only to specialists in physics and semiconductor technology but also to the common public. But these structures of nanoscopic dimensions appeared several decades ago in the vision of renowned specialists in these materials and, as a reality, after it was possible to develop epitaxial crystal growth techniques and methodologies that allow ultra-precise control of the deposition of atomic monolayers. The 1980s witnessed a steady increase in research work on these structures. The subsequent decades have seen the consolidation of a branch that has redefined solid-state physics and, in particular, semiconductor physics. Although these three classes of systems began to be studied, at least from a theoretical point of view, almost simultaneously, the attention of the first years was much more inclined towards quantum wells.