Supply

Supply (also Psi or Control) determines the maximum army size you can have at a time. Supply maxes out at 200 and your limit is raised by either building specific buildings or Units (Terran: Supply Depot or Command Center, Protoss: Pylon or Nexus, Zerg: Overlord or Hatchery). Each unit has an amount of Supply that it consumes varying from 0.5 for Zerglings and Scourge to 6 for Battlecruisers and Carriers.

Failure to produce additional supply results in supply block and should be avoided to maintain a healthy growing economy.