The Protoss Scout is a Deep-Space/Aerospace recon craft, as the name suggests. It was originally intended for such, but the conflicts with the Zerg and the Terran Dominion has pressed it into combat service. It is suited for dogfighting, but can also take out ground targets such as Sunken Colonies.
The Scout has fallen into disuse after the Brood War had begun, and has been replaced with the new Phoenix starfighter.
Using Scouts: Like the Overlord, the Scout is not very useful until it gets the appropriate upgrades. Its antimatter missiles can dish out some serious punishment against enemy aircraft, but anti-air defenses will have no trouble swatting it out of the sky. A cohort of Scouts and/or Corsairs should be used to escort Shuttles, Carriers and Arbiters.
Fighting Scouts: By the time the Protoss are sending in Scouts, there's a good chance you've got a good array of SAMs. If not, improvise with Marines, Goliaths or Hydralisks. DO NOT use air units against scouts, especially Mutalisks, or else they'll be obliterated by a salvo of antimatter missiles.
Unit Class: Protoss Aircraft, Interceptor/Scout(durr)
Weapons: Photon Blasters(Air to Surface), low damage, low rate of fire. Antimatter Missiles(Air to Air). high damage, high rate of fire.
Air Attacks: Increases the attack power of Protoss Aircraft. Researched at Cybernetics Core.
Air Armor: Increases the armor strength of Protoss Aircraft. Researched at Cybernetics Core.
Plasma Shields: Increases the power of Protoss Plasma Shields. Researched at Forge.
Apial Sensors: Enhanced sensors are installed into the fore of the Scout, increasing its line of sight. Researched at Fleet Beacon.
Gravitic Thrusters: By utilizing gravitonic technology in the Scout's propulsion systems, it is able to move faster. Researched at Fleet Beacon.