Check out the website for the Sailing Committee (Qingdao) of the Beijing Organising Committee for the Games of the XXIX Olympiad.
It lists some helpful information for non-sailors wanting to understand the sport better...
A typical racing sailboat has many parts such as the mast, boom, hull, keel and rudder. Mainly there are five types of racing sailboat. Respectively they are,
Keel Boat. As it's name implies, keelboat has a keel to help it go straight in the water. Keelboat is a large, heavy, stable, and multi-people controlled boat that is more suitable on long distance sailing.
Centerboard Boat or Dinghy. It is a light, flexible, inexpensive boat with a small rudder behind. One of the most popular sailboat in Olympics.
Multi-Hull. It is constructed by more than one hull. The boat is distinctive on its speed and excitement.
Tower ship. A giant boat mostly being used for amusement proposes.
Windsurf. No rudder, no fin, easy to operate.
Sail-World is eagerly looking forward to reporting on the Tower ship class - just for the 'amusement proposes'.