-Zerg- The zerg are a carniverous breed. They live to kill and have adapted to the protoss and terran technologies. Like they have figured out how to open doors (etc.) They don't build or warp in buildings, they morph them from drones. and they don't train or warp in units, They morph them from larva. They have carapraces that when attacked, heal themselves
-Terran-The Terran are humans, only more advanced than us. They are in battle to protect thier home planet, Earth. The terran can build with SCV's and they can repair, unlike any other breeds. They have medics for the organic units like Marines.
-Protoss- The protoss use Psionic Energy to defeat their enemies. There are protecting their home planet, Aiur. And instead of building or morphing buildings, they warp in buildings that are built on thier home planet Aiur. They have shields on each of their units, instead of recovering, or healing/repairing, the shield recover but not thier HP. They are the most powerfullest of the 3, but it takes the longest time to build up a force.