The paper is a naive introduction to descriptive set theory. It is aimed mathematicians without a background in logic. The goal is to provide the basic facts used for applications of descriptive set theory to other areas of mathematics, particularly analysis and dynamical systems. The only topological or set theoretic background required is covered in undergraduate courses. It covers the hierarchy of Borel sets and the analytic sets, trees, Suslin's operation A, reductions, norms, separation theorems and uniformization.