This book gives a comprehensive overview of the current observational and theoretical status in the field of the local and general interstellar medium. It contains contributions presented at the IAU Colloquium No. 166. Review articles and highlight talks will serve both as an introduction to the field for the undergraduate or the non-specialist and also give a summary of the most recent developments for the expert and researcher. These articles are supplemented by a representative number of original research papers. All contributions are fully refereed and have been edited with extensive care to provide a high-standard reference book. The scientific content spans a wide range from solar system measurements of dust grains to X-ray emission from distant galaxies.