The interacting boson approximation

The IBA-1 is reviewed with particular emphasis on the symmetry structure that arises naturally from its inherently algebraic approach. The formulation of the model, in both its algebraic and its numerical aspects, is presented and the basic character of its predictions is discussed and compared with nuclear data. The limitations of the model, and efforts to ameliorate these by appropriate extensions, are also reviewed in some detail. An effort is made to provide a simple, transparent understanding of the basic physics by clarifying the relation of the mathematical structure to underlying physical ideas, and to provide guidance in understanding and carrying out practical calculations.