Abstract. I will review recent progress in the understanding of the AdS3/CFT2 correspondence with pure NS-NS flux. I will explain the computation of the spectrum and the correlation functions of the worldsheet theory and how they are matched with the recently proposed dual CFT. I will also discuss the simplifications that occur in the tensionless limit where the background AdS3xS3xT4 is dual to the usual symmetric orbifold of T4. In this limit, the correspondence is under sufficient control to probe AdS/CFT non-perturbatively and say something about the emergence of geometry and background independence in string theory.