The Optimist is the most popular sailboat in the world.  It is traditionally used as a trainer for sailors under 14 years of age who weigh less than 110 pounds.  It is a single-handed boat with a rig that is 3.3 square meters.  The origin of the unique hull design is due to the original version of the boat to be made as a home project.  It went from humble beginnings to being an international racing sensation.  The hull is square in shape because it is based off of designs for a boat to be built out of plywood and other home goods, in theory to make sailing more accessible.  Today it boasts being one of the largest racing fleets in the world, and every year there are numerous regattas with hundreds of boats competing in each.  The modern version of the hull is 77 lbs of fiberglass and gelcoat.
The Optimist has become the standard for learning to race on the East Coast.  Children learn how to find the direction of the wind and then how to move the boat forward using small nuances in technique that have big effects on racing results.  Tactics are important in the boat because of the relatively similar boatspeed, large fleets, and varying course sizes.
During the summers we usually have about 100 Optimists sailing within our junior programs.  During the Fall, Winter, and Spring we have a number of sailors that compete at the highest levels regionally, nationally, and internationally.  The Optimist World Championship has attracted so many young sailors that a qualification system consisting of several tiers has been put into place to limit the numbers.