The primary goal of this text is to explore the physical properties of polymers in confined spaces at the nanometer scale, with a particular emphasis on determining the mechanisms by which polymers are transported through narrow interstices. A variety of pore structures that polymers can penetrate have been discovered, and it is now possible to probe the dynamics of the interactions between polymers and the penetrating molecules. The experimental and theoretical advances discussed include: mechanical properties of single molecules; detection and characterization of single polymers transported through narrow ion channels; direct measurement of the energetics and dynamics of polymer transport through a pore; statistical mechanical theories for single polymer transport through a narrow pore; novel polymer separations techniques not based on cross-linked gels; and physics of polymer-protein interactions. The book also explores potential scientific and technological applications that can exploit these systems, with the aim of stimulating new research in this highly multidisciplinary field.