Fusion energy has now emerged as one of the most disruptive technology opportunities, attracting the attention of risk-tolerant investors and large amounts of private capital. This book examines the emergence of nuclear fusion technology as a commercial proposition, grounded in both technological opportunities and high-technology business development. The book introduces a broad range of possible commercial fusion technologies and various pathways to commercialization are described. While the prospect of grid-scale fusion electricity is a major motivator, it is not the only, nor the easiest, path to first commercialization. Reflecting the background of the editorial team, the book has a particular focus on developments in Japan and the UK – two leading fusion nations. A such, it gives weight to developments in these two countries at the forefront of fusion innovation but the book has a global outlook and developments elsewhere, especially in the United States, are also considered. The scientific and technical basis of fusion is introduced sufficient to appreciate the range of innovation in the sector and to illustrate why fusion is attracting billions of dollars of private sector investment. The relationship of private sector firms to state-funded research laboratories is discussed as both help drive the technology forward to deployment. Various business models for fusion technology are explored, from the monetization of fast fusion neutrons through to the generation of baseload grid-scale electricity. The book helps the reader appreciate the diversity of fusion innovation and hence separate the hype from the reality.