Boom - The horizontal pole or spar attached to the mast and the bottom of the sail.

Bow - The front of the boat.

Buoy - A floating marker.

Capsize - When a boat overturns.

Centreboard - An adjustable fin primarily used to stop the boat moving sideways through the water. Also called daggerboard.

Course - The route which the boats must sail to complete the race.

Daggerboard - An adjustable fin primarily used to stop the boat moving sideways through the water. Also called centreboard.

Dinghy - e.g. Laser, Laser Radial, 470, Finn - the dinghies used at the Olympics - they all have a one hull and a centreboard or daggerboard.

Downwind - Boats sailing downwind have the wind behind them. If a boat has a spinnaker it will be used while sailing downwind.

Fleet Racing - Competition format were entries race against each other around a course, this format is used by 9 of the 10 Olympic events.

Genoa/Headsail/Jib - The smaller sail set infront of the mast.

Hiking/hike out - To lean out over the side to balance the boat against the force of the wind.

Jury - The group of Rules experts who decide the outcome of protests.

Keelboat - e.g. Star, Elliott 6m- A boat with a "keel" - the fin attached to the bottom that prevents it from capsizing and stops it moving sideways through the water.

Kite (asymmetric) - A large, often colourful sail used during downwind sailing set in front of the other sails (carried by the 470, 49er and Elliott 6m) The 49er uses an asymmetric spinnaker. Also called spinnaker.

Knot - A measure of wind speed 1 knot = 1 nautical mile per hour, 1.15 mph and 1.85 km/h.

Leeward - The side furthest away from the wind.

Mainsail - The sail behind the mast.

Mast - The vertical spar or pole to which the sail(s) are attached.

Match Racing - Competition format where two identical boats race against each other.

Medal Race - The final race in the series. Only the top 10 boats after the opening series compete and scores are doubled.

Multihull - e.g. Tornado (used at the Olympic Games from 1976 to 2008) - A boat with more than one hull. A boat with two hulls is also known as a catamaran and a boat with three hulls is knows as a trimaran.

Port - The left hand side of a boat when looking forward. A boat is on "port tack" when the wind is coming from the left.

Protest - A claim that another boat has broken the Rules.

Race Officials - The Officials responsible for running the race and enforcing the Rules. This group includes the Measurers who ensure that each sailor's equipment is equal and within the rules, the Race Officers who run the races and the Judges and Umpires who are rules experts and make decisions about whether rules have been broken.

Rudder - Attached to the tiller the rudder is used to stear the boat.

Sheet - A rope used to control a sail.

Skiff - e.g. 49er - A light open dinghy with a self draining hull.

Slalom finish - A technical section of the windsurfing (RS:X) course involving multiple changes of direction in quick succession.

Spinnaker - A large, often colourful sail used during downwind sailing set in front of the other sails (carried by the 470, 49er and Women's Match Racing) The 49er spinnaker is asymmetric. Also called kite.

Starboard - The right hand side of a boat when looking forward. A boat is on "starboard tack" when the wind is blowing from the right.

Stern - The back of a boat

Tiller - The handle attached to the rudder used to steer a boat

Trapeze - A wire attached to the mast to which a sailor wearing a harness attaches him/herself. It enables them to position their weight further out of the boat providing greater balance against the boat heeling over. Used on the 470 and 49er.

Upwind - Sailing upwind means to sail towards the direction the wind is coming from. A boat cannot sail directly into the wind so will sail a zig zag course to reach the upwind (windward) mark.

Windsurfer - e.g. RS:X - The board, sail, mast etc on which the sailor stands up.

Windward - The side closest to the wind.