The book "Fields and Particles" offers a comprehensive collection of lectures delivered during the 29th International University Weeks for Nuclear Physics in Schladming, Austria, in March 1990. The lectures were presented by leading experts in the field of quantum field theory and cover some of the most current and intensely discussed topics. The careful revision of the lecture notes by the authors ensures a high quality of content. This specialized book is aimed at students and professionals who wish to engage with the complex aspects of integrable models and conformal field theory. The topics are both theoretical and application-oriented, providing valuable insights into modern physics. Support from various sponsors, including the Austrian Ministry of Science and Research, has made it possible to compile this significant collection of knowledge.