The multiparticle systems dealt with here - gases, nanosystems and fluids - involve all forms of matter that are to be categorized between particles (Constituents of Matter, Volume 4) and solids (Volume 6). Experiments are emphasized and in addition, all major theoretical initiatives and approximations as well as all current major discoveries are described by leading experts. Nanoparticles and functional nanosystems have been the subject of increasing interest over recent years, including for practical applications. Their production, the analysis of their physical properties and their application are fully described. Key Features - comprehensive description of the complex field of multiparticles incorporating all current major discoveries - suitable for compiling material for self-study.