Wave energy is reaching a critical stage, following over three decades of intensive research and development. The first few full-scale prototypes have been tested at sea and the first pre-commercial orders were placed. The first offshore wave farm is to be installed in the near future and it is likely that similar schemes will shortly follow. Such projects will in the medium term provide a comparable output to the conventional wind farms, allowing an alternative approach when trying to ov- come the technological challenge of finding alternative renewable energy sources. It will also fulfil one of the oldest desires of civilization: to harness the power of ocean waves. This book compiles a number of contributions prepared with the aim of prov- ing the reader with an updated and global view on ocean wave energy conversion. Given the topics covered and the link between of all them, it can be considered one of the first textbooks (or handbooks) related to this field. The authors are r- ognised individuals within the wave energy community with different ba- grounds, and their contributions try to give an overall perspective of the state of the art of different technologies. The book does not intend to point to a specific technology; the market will be responsible for that.