This building is the center building of the Zerg Swarm.The building produces larvas with time and player converts /morphes them into the Zerg units.The maximum number of larvas is three.We made test about the nature of larva production and we observed that after lots of units (overlord test,we produce hundreds of overlords) the Hatcheries did not produce larvas and that was the extreme border of Zerg production.The Hatcheries has some advantage, first these buildings are living that means they regenerate their life energy.The building is chip also and the production style is unique which gives Zerg Swarm a very rapid expansion rate.Early exp tactic is commonly used by Zerg players because the tactic is safe and efficient.But when you are performing this tactic be sure that the number of sunkens are enough if they are not the enemy can infiltrate into your defenses and you will loose the game.