This is the fourth and last volume of the invaluable publication At the Frontier of Particle Physics: Handbook of QCD. In this volume the reader will find three important sections. The first is devoted to QCD-based phenomenology. It covers issues deeply woven into the fabric of particle physics: weak interactions of light quarks (J Bijnens) and heavy quarkonium physics (A Hoang). The second section is a report on recent advances in the understanding of confinement in three dimensions in the Georgi–Glashow model (I Kogan and A Kovner). The third section deals with lattice QCD (A Kronfeld) and loop equations (A Dubin and Yu Makeenko).

The five reviews in Volume 4, together with the 33 reviews in Volumes 1–3, constitute a full encyclopedia, covering all aspects of quantum chromodynamics as we know it today. The articles have been written by recognized experts in this field. Combining features of a handbook and a textbook, this is the most comprehensive source of information on the current status of QCD. It is intended for students as well as physicists — both theorists and experimentalists.