“…In this way we aim to illustrate how each successively more abstract framework-first passing from friezes to cluster algebras, and then to cluster categories-can lead to clean explanations of phenomena appearing at the previous level. This path can be followed further than we have space to do here, and leads to, for example, the theory of quivers with potential [24] and their more general cluster categories [2], Frobenius cluster categories and their applications to cluster algebras appearing in geometry [12,41,52,64,65], Adachi-Iyama-Reiten's τ -tilting theory [1], and the theory of stability conditions and scattering diagrams [10,11,45].…”