  In recent years the topic of localized wave solutions of the homogeneous
scalar wave equation, i.e., the wave fields that propagate without any
appreciable spread or drop in intensity, has been discussed in many aspects in
numerous publications. In this review the main results of this rather disperse
theoretical material are presented in a single mathematical representation -
the Fourier decomposition by means of angular spectrum of plane waves. This
unified description is shown to lead to a transparent physical understanding of
the phenomenon as such and yield the means of optical generation of such wave
fields.
