This book covers various experimental and theoretical aspects of multiparticle production in high energy interactions from lepton-lepton, lepton-hadron, hadron-hadron, hadron-nucleus and heavy ion collisons. This is the first time that data from CERN LEP, FNAL, DESY, BNL AGS, CERN SPS and BNL RHIC have been collected in a single volume. Not only accelerator-induced reactions but also cosmic ray interactions of very high energy are discussed, and the up-to-date theoretical interpretations are summarized.