The past decade has seen a qualitative advancement of our understanding of physical phenomena involved in flow separation in supersonic nozzles; in particular, the problem of side loads due to asymmetrical pressure loads, which constitutes a major restraint in the design of nozzles for satellite launchers. The development in this field is to a large extent motivated by the demand for high-performance nozzles in rocket engineering. The present paper begins with an introduction to the physical background of shock-boundary-layer interactions in basic 2D configurations, and then proceeds to internal axisymmetric nozzle flow. Special attention is given to past and recent efforts in modeling and prediction, turning physical insight into applied engineering tools. Finally, an overview is given on different technical solutions to the problem if separation and side loads, discussed in the context of rocket technology.