In 1972, Bratteli introduced a class of graded infinite graphs, later called Bratteli diagrams, in order to classify the approximately finitely (AF) C*-algebras. After the Vershik's study, Bratteli diagrams turned out to be a powerful and productive tool for the study of dynamical systems. In this talk, we first review the efinitions of Bratteli diagrams and dimension groups, and then we discuss the well-known results and open problems on Bratteli diagrams in various aspects.