This book covers MASS regulation, technology, and policy. MASS development began with the realization of the 4th industrial revolution technologies such as big data, AI, IoT, and communication, which were also linked to technological development in the maritime field. However, it is still unclear how MASS will operate. This book is divided into three parts: MASS regulation, technology, and policy, and explains each part in detail. Part I “MASS regulation and safety� deals with IMO works for MASS, including IMO MASS RSE results which has been finished in 2021. In addition, the United Nations Convention on the Law of the Sea (UNCLOS), one of the most important international conventions to be considered for MASS operation, will be dealt with and various safety considerations will be explained in detail. Through this, this book explains in detail the regulatory considerations and safety considerations for MASS. In particular, the gaps and themes identified in IMO MASS RSE and the priority discussion needs are explained, and based on this, the development of a goal-based non-mandatory MASS code currently in progress is discussed. UNCLOS is a convention like the blueprint of the IMO Conventions, and it is very important to understand and meet the requirements of UNCLOS for the operation of MASS. Therefore, this book provides a detailed explanation of the application of UNCLOS. In particular, UNCLOS Article 94 would be a very important consideration. Also, this book covers COLREGs and technologies for MASS operations.