The utilization of renewable energy sources is a vital aspect for development of sustainability. Currently, an unexploited energy source is ocean waves. Various types of wave energy converters (WECs) are able to transform the motion of the waves into electricity. During the last 30 years, a wide range of prototypes was presented with different rates of success. The aim of this survey is to give an overview of how WECs are categorized [operation principle and power takeoff (PTO) system] and show what are the most important criteria that have to be kept in mind when designing a WEC. A few important WECs are described and evaluated.