Book excerpt: This book introduces the new concept of “nanozyme”, which refers to nanomaterials with intrinsic enzymatic activity, rather than nanomaterials with biological enzymes incorporated on the surface. The book presents the cutting-edge advances in nanozyme, with emphasis on state-of-the-art applications in many important fields, such as in the biomedical fields and for environmental protection. The nanozyme is a totally new type of artificial enzyme and exhibits huge advantages over natural enzymes, including greater stability, low cost, versatility, simplicity, and suitability for industry. It is of interest to university researchers, R&D engineers, as well as graduate students in nanoscience and technology, and biology wishing to learn the core principles, methods, and the corresponding applications of “nanozyme”.