π-π Interactions are the dominating supramolecular forces in systems like carbon nanostructures, which are inherently constituted by large conjugated π-systems. Their skilful use has allowed the construction of fascinating supramolecular ensembles, thus opening a new avenue in carbon chemistry. In this tutorial review, we provide a short introduction to carbon nanostructures, and show the basic concepts of π-π interactions involving fullerenes, carbon nanotubes, and graphene.