A map f : [0, 1] → [0, 1] is a piecewise contraction if locally f contracts distance, i.e., if there exist 0 < λ < 1 and a partition of [0,1] into intervals I1,I2,...,In such that |f(x) − f(y)| ≤ λ|x − y| for all x, y ∈ Ii (1 ≤ i ≤ n). Piecewise contractions describe the dynamics of many systems such as traffic control systems, queueing systems, outer billiards and Cherry flows. Here I am interested in the symbolic dynamics of such maps. More precisely, we say that an infinite word i0 i1i2 . . . over the alphabet A = {1, 2, ..., n} is the natural coding of x∈[0,1] iff k(x)∈Ik for all k≥0. The aim of this talk is to provide a complete classification of the words that appear as natural codings of injective piecewise contractions.