he Optimist is a small, single-handed sailing dinghy intended for use by children up to the age of 15. Contemporary boats are usually made of fibreglass, although wooden boats are still built.

It is one of the most popular sailing dinghies in the world, with over 150,000 boats officially registered with the class and many more built but never registered.

The Optimist is recognized as an International Class by the International Sailing Federation.

While younger lighter sailors begin in Optimists, competitive sailors usually weigh between 35 and 55 kg (or between 80 lbs. and 125 lbs.).[9]Optimists can be sailed by children from age 8 to 15. This wide range of weights which is not typical of most dinghies is made possible by different cuts of sail. Due to its inherent stability, unstayed rig, robust construction and relatively small sail, the Optimist can be sailed in winds of up to 30 knots.

Optimists are manufactured to the same specification by over 20 builders on four continents. There is strong evidence[10] that hulls from different builders are the same speed. Sails and spars of differing qualities enable sailors to upgrade their equipment as they progress.

The Optimist is the slowest dinghy in the world according to the RYA Portsmouth Yardstick scheme, with a Portsmouth number of 1646.[11] Its equivalent rating in the US scheme is a D-PN of 123.6.[12]