This book provides a systematic and comprehensive overview of knowledge graph, covering all aspects including the theoretical foundations, key techniques and methodologies, and various typical applications. Special focus is given to the practical methods for knowledge graph construction and management, especially methods for constructing knowledge graphs from texts and from Encyclopedia, and methods for knowledge fusion and reasoning. It can serve as reference book for researchers and students new to knowledge graph. From this book, the readers will learn how to construct large-scale knowledge graphs from different sources, how to manage multiple knowledge graphs and do reasoning with a knowledge graph. Some basic knowledge on discrete mathematics, probability and statistics, data structure, and databases is required to understand the book content well.