Guest Editors' Preface: The International Conference on Ultrashort High-Energy Radiation and Matter

The International Conference on "Ultrashort High-Energy Radiation and Matter" has been held in Villa Monastero, Varenna, Italy, during October 7–10, 2003. The conference has been jointly organized by the "Piero Caldirola" International Centre for the Promotion of Science and International School of Plasma Physics, Milan, Italy, and by the FEMTO Programme of the European Science Foundation (chaired by Prof. Charles Joachain of the University of Bruxelles)