Wave energy research and development has been taking place for about 25 years now, with some progress towards exploiting the large energy potential of the world's ocean wave climates. Such an environmentally benign source of energy is highly desirable as it could contribute significantly to a sustainable energy future. Ocean waves are often powerful, but with extremely low frequencies of about 0.1 Hz (periods of around 10 s), and the success in generating electricity depends upon achieving a rotation of typically 1500 rpm. This paper considers the size and characteristics of wave resources, looks at some of the technologies most likely to be deployed to extract energy from waves and briefly mentions the economic assessment.