The first of two volumes, this text provides an introduction and comprehensive review of the physics of highly charged ions. Dealing with sources, applications and fundamental processes, it covers a wide range of topics varying from cancer therapy to tests of quantum electrodynamics. Fusion related processes and those pertaining to astrophysics receive comprehensive coverage as well as theoretical and experimental treatments of the fundamental processes in which highly charged ions can become involved. All of these subjects are covered and findings are reviewed.