Scouts are Protoss space fighters known for their effectiveness against enemy capitial ships and ground forces with both antimatter missiles and photon blasters respectively.
These fighters also have the dual purpose of exploration during times of peace. Some Dark Templar variants are outfitted with FTL technology made for travelling through the Void.
Four years after the Brood War, the Scout-class starfighter has begun to be replaced by the Phoenix-class starfighter, although the Scout remains in use by the Savrai caste.
In the game series, the Scout is a Protoss space superiority fighter.
For more information see Scout on the parent site