Both from a morphological and a functional point of view, the nucleus is central to modern cell biology. Transport of proteins and RNAs between the nucleus and the cytoplasm continues to be a fascinating research topic on its own. Furthermore, it affects many aspects of gene expression and general cellular functions and has far-reaching implications for human health. In this book, we cover a wide range of topics from the nuclear transport field. Individual chapters deal with the general concepts of nucleocytoplasmic transport, with various transport pathways like nuclear protein import, mRNA export and tRNA trafficking, and with the molecular mechanisms that govern macromolecular exchange between the two compartments. Others address new technologies that will help to answer open questions in the future. Together, we hope to provide a collection of reviews that should be useful for experts in the field, as well as for a wider audience.