This volume deals with physical properties of electrically one-dimensional conductors. It includes both a description of basic concepts and a review of recent progress in research. One-dimensional conductors are those materials in which an electric current flows easily in one specific crystal direction while the resistivity is very high in transverse directions. It was about 1973 when much attention began to be focussed on them and investigations started in earnest. The research was stimulated by the successful growth of crystals of the organic conductor TTF-TCNQ and of the inorganic conductor KCP. New concepts, characteristic of one dimension, were established in the in vestigations of their properties. Many new one-dimensional conductors were also found and synthesized. This field of research is attractive because of the discovery of new ma terials, phenomena and concepts which have only recently found a place in the framework of traditional solid-state physics and materials science. The relation of this topic to the wider field of solid-state sciences is therefore still uncertain. This situation is clearly reflected in the wide distribution of the fields of specialization of researchers. Due to this, and also to the rapid progress of research, no introductory book has been available which covers most of the important fields of research on one-dimensional conductors.