A proa, also seen as prau, perahu, and prahu, or prow, is a type of multihull sailboat. It is a vessel consisting of two (usually) unequal length parallel hulls. It is sailed so that one hull is kept to windward, and the other to leeward, so that it needs to "shunt" to reverse direction when tacking. The English term proa usually refers specifically to the South Pacific proa as described in the journals of the British ship HMS Centurion.
The perahu traditional outrigger boat is most numerous in the various islands of Indonesia, Malaysia, and the Philippines. These differ from the South Pacific vessels. Traditional proas superficially resemble outrigger canoes, but have a buoyant lee hull and a denser, ballasted hull to windward for stability.
To Americans, the boats of the Marianas Islands are arguably the most recognizable version.
The modern proa exists in a wide variety of forms, from the traditional archetype still common in areas described, to high-technology interpretations specifically designed for breaking speed-sailing records.