In 1977, Milnor and Thurston introduced a combinatorial theory for piecewise monotone continuous maps of the interval. The main ingredient is the use of symbolic dynamics, this idea was developed earlier by Parry in 1964 and Metropolis, Stein, and Stein in 1973. In this talk, we will explain the basic constructions of the kneading theory and how these are related to the Artin-Mazur zeta function.