Book excerpt: This volume includes 28 contributions to the Toyoichi Tanaka Memorial Symposium on Gels which took place at Arcadia Ichigaya on September 10th-12th, 2008. The contributions from leading scientists cover a broad spectrum of topics concerning: Structure and Functional Properties of Gels - Swelling of Gels - Industrial and Biomedical Application. The symposium was held in the style of Faraday Discussions, which stimulated the active discussion. After the symposium, each manuscript was rewritten based on the discussion and the critical review. Since the research on gels is becoming more and more important both for academia and industry, this book will be an essential source of information.