The potential of electric power generation from marine renewable energy is enormous. Ocean waves are being recognized as a resource to be exploited for the sustainable generation of electrical power. The high load factors resulting from the fluid properties and the predictable resource characteristics make ocean waves particularly attractive for power generation and advantageous when compared to other renewable energies. Regarding this emerging and promising area of research, this paper presents a complete review of wave energy technologies describing, analyzing and fixing many of the concepts behind wave energy conversion. The proposed review will specifically highlight the main wave energy conversion projects around the world at different levels (demonstration stage, in production, and commercialized projects). In addition, a discussion will highlight challenges that wave energy converters need to overcome to become commercially competitive in the global energy market.