In Starcraft, the Corsair is the Protoss extension of the Air Balance Model. An inexpensive aircraft produced at the Stargate, it is less sturdy than the Scout, and its main attack- an anti-air weapon exclusively- only does five points of damage, making it very weak against airborne units with strong armor such as the Battlecruiser or the Carrier.
However, when the Corsair is brought in numbers against packs of other, weaker air units, it truly begins to shine. While its attack only does five damage, its cooldown rate is very low, meaning it attacks roughly twice every second on the faster speeds- and this damage is splash damage, making it a murderous weapon against unsuspecting packs of Mutalisks or Wraiths.
In longer games, the special ability of the Corsair often enters play. Disruption Web is a potent ability, and a Protoss player can waltz through a base with a pack of Dragoons if they are supported by enough Corsairs.