Types of Reefs:

FRINGING REEFS grow in shallow waters and project out to sea from the shores of islands or continents.  They consist of several zones that are characterized by depth, structure, and the plants and animals living in it.
BARRIER REEFS are platforms separated from the land nearby by a bay or lagoon.
ATOLLS develop near the surface of the sea when islands that were engulfed in reefs sink.  Atolls separate lagoons and are usually circular.

Locations of Reefs:

Coral reefs are located in tropical or sub-tropical temperatures all over the world.
The longest barrier reefs occur off the coasts of Australia and Belize.  Reefs are mostly located in: the tropical Americas (Bahamas, Bermuda, Florida, etc.), East Asia (Singapore, Japan, Thailand, etc.), the Pacific (Australia, New Zealand, Papua New Guinea, etc.), Indian Ocean (Kenya, Somalia, Tanzania, etc.), and the seas of the Middle East (Saudi Arabia, Sudan, Yemen, etc.)
 
 

The Great Barrier Reef Marine Park                                                        Map of coral reefs around world.