This book establishes the scientific definition of M&A for the first time, that is, M&A is a transaction targeted at business control. Based on this, the book established a theoretical framework of mergers and acquisitions with its 8 core pillars, including motivation, capability, boundary, direction, matching, synergy, performance and market. The theories of mergers and acquisitions will well explain the strategy, valuation, integration and other activities of M&A.