the understanding of functional groups is key for the understanding of all organic chemistry. in the tradition of the patai series each volume treats all aspects of functional groups. each volume contains chapters on the theoretical and computational foundations; on analytical and spectroscopic aspects with dedicated chapters on mass spectrometry, nmr, ir/uv, etc.; on reaction mechanisms; on applications in syntheses. each volume includes chapters on applications. depending on the functional group there are usually chapters on industrial use, on effects in biological and/or environmental systems. the series has recently published two volumes on organolithium chemistry. it seems appropriate to now publish a volume on magnesium, as the two metals remain unique in reacting with organic halogen compounds. the field has seen steady progress, and a volume on this topic has long been overdue.