The International Ten Metre Class is a construction class, meaning that the boats are not identical but are all designed to meet specific measurement formula, in this case International Rule.

At their heyday, Metre Classes were the most important group of international yacht racing classes, and they are still actively raced around the world.

"Ten" in class name does not, somewhat confusingly, refer to length of the boat, but product of the formula; 10 Metre boats are, on average, 16.5 meters long.

[1] The International Rule was set up in 1907 to replace earlier, simpler handicap system which were often local or at best, national, and often also fairly simple, producing extreme boats which were fast but lightly constructed and impractical.

The rule changes several times in history.