The theory of virtual distortions provides an efficient tool which can be used to treat many problems that differ from the physical point of view. The objective of this book is to present a general concept of the Virtual Distortion Method with the necessary theoretical background and a variety of its applications to problems of structural analysis and design. The book is focussed more on theoretical aspects of the problems than on the practical design of structuré. Nevertheless, a number of numerical algorithms discussed in the book has already been developed as a computational system capable to solve various problems of structural analysis.