Abstract: Frieze is an array of positive integers satisfying certain rules.  Friezes of type A were first studied by Conway and Coxeter in 1970's, but they gained fresh interest in the last decade in relation to cluster algebras.   Moreover, the categorification of cluster algebras developed in 2006 yields a new realization of friezes in terms of representation theory of Jacobian algebras.   In this talk, we will discuss friezes of types A and D and their mutations.