On the Formation of Jets
  The phenomenology of jets associated with a variety of black hole systems is summarized, emphasizing the constraints imposed on their origin. Models of jet formation are reviewed, focusing in particular on recent ideas concerning MHD models. Finally, the potential for advancing our understanding of jets both through future observations - especially forthcoming X-ray missions - and for elucidating some crucial theoretical questions is highlighted. 
Annalisa Celotti (1) and Roger D. Blandford (2) ((1) SISSA, Trieste,   Italy, (2) Caltech, Pasadena, USA)