The previous chapters of this book have defined ‘carbon-neutral products’ conceptually as products whose carbon emissions produced during the production, use, and recycling processes are completely offset and eliminated, also known as ‘zero-emission products’. Based on this definition, this book proposes the definition of ‘carbon-neutral design’, which is a systematic design of the entire production, use, and recycling process of a certain product to achieve the goal of Carbon Neutrality, so that its carbon emissions are completely offset and eliminated. The product referred to here is not only the narrowly defined products used in daily life, but also macroscopic things such as industrial systems, buildings, towns, and the environment. The design mentioned here has evolved from the design of a certain product to the concept of ‘big design’, which is a comprehensive and complex plan implemented to achieve a specific goal or vision. In achieving the goal of Carbon Neutrality, big design can be reflected in city planning, construction engineering, environmental engineering, product production, information technology, enterprise management, and many other aspects. The core goal of big design is to create long-term value and sustainable solutions through systematic and comprehensive methods.