Advances in Physics publishes authoritative critical reviews by experts on topics of interest and importance to condensed matter physicists. It is intended for motivated readers with a basic knowledge of the journal's field and aims to draw out the salient points of a reviewed subject from the perspective of the author. Advances in Physics has recently started a new section, Perspectives, complementing its regular reviews with occasional shorter more provocative articles by leaders in their fields in order to stimulate debate in the community. These articles will present concise perspectives on topics of major current interest. Advances in Physics is the Number One Condensed Matter Physics Journal (ISI 1998, 1999). The current impact factor is 13.438.