Reef Break Waves
are generally surfed by more experienced surfers...somewhere in the intermediate to advance range in abilities. Reef Breaks are usually waves breaking over of solid coral reef or rock ledge. The best places to surf these waves are near the end of the reef where the wave can drop off into deeper water. This helps shape the wave the runs along a reef break as well as giving the surfer a safer place to exit and paddle back out.
Depending the the swell direction and strength, reef breaks are usually fairly predictable in terms of where the "take off" spot should be and the general wave the wave will break across the reef. But they usually break in shallow water, which can be extremely hazardous. Not ideal for beginners, and the size and intensity of the wave will determine how an intermediate or advanced surfer might surf the wave.
You can learn more about how waves are formed here: Where Do Waves Come From
, and get a better understanding of how the waves will work over a reef break