Physical layer security (PLS) draws on information theory to characterize the fundamental ability of the wireless physical layer to ensure data confidentiality. In the PLS framework it has been established that it is possible to simultaneously achieve reliability in transmitting messages to an intended destination and perfect secrecy of those messages with respect to an eavesdropper by using appropriate encoding schemes that exploit the noise and fading effects ofwireless communication channels. Today, after more than 15 years of research in the area, PLS has the potential to provide novel security solutions that can be integrated into future generations of mobile communication systems. This chapter presents a tutorial on advances in this area. The treatment begins with a review of the fundamental PLS concepts and their corresponding historical background. Subsequently it reviews some of the most significant advances in coding theory and system design that offer a concrete platform for the realization of the promise of this approach in data confidentiality.