Zerg Part 1

The zerg were "created" by the xel'naga on Zerus. The xel'naga were intrigued by their purity of essence. However, the zerg leader, the Overmind, grew beyond its creators' control and ordered the Swarm to destroy them. It became aware of the protoss.
The zerg traveled in the general direction of Aiur. Discovering the terrans, the Overmind hoped to assimilate their psionic potential so it could defeat the protoss. When the zerg infested Chau Sara, however, the protoss, who were now aware of their presence in the Sector, destroyed all life on the planet.

The zerg eventually defeated the Terran Confederacy, launching a massive invasion against the Terran Confederacy capital world of Tarsonis after being guided there by the Sons of Korhal rebel movement leader, Arcturus Mengsk. While there, the zerg captured a psionic terran named Sarah Kerrigan, transporting her to Char, infesting her and transforming her into the powerful Queen of Blades.

Kerrigan's presence drew the protoss leaders Tassadar and Zeratul to Char. The latter was a Dark Templar with the ability to permanently slay cerebrates. Striking an alliance, the two protoss groups fought repeated battles against zerg forces led by Infested Kerrigan. Zeratul slew Zasz, inadvertently giving the Overmind the location of Aiur. The majority of the Zerg Swarm promptly traveled to Aiur, leaving Kerrigan behind with a small number of zerg to fight the protoss still on Char. The zerg on Aiur enjoyed victories over the protoss.
The protoss on Char eventually escaped to Aiur, where they were able to defeat the Overmind.
The temporarily leaderless zerg overran Aiur, killing most of its population. The zerg split into two factions, one led by Daggoth (and the second Overmind) and the latter led by Infested Kerrigan. The protoss fled to Shakuras followed by Daggoth's zerg. The protoss collected a pair of artifacts in order to destroy the zerg and make their new home safe, while forming an unexpected alliance with Kerrigan. The protoss destroyed the zerg on Shakuras in order to protect themselves, belatedly realizing that Kerrigan was manipulating them into fighting on her side in the zerg civil war.

The arrival of the United Earth Directorate in the Koprulu Sector upset Kerrigan's plans. After conquering the Terran Dominion and chasing after its emperor, Arcturus Mengsk, they took control of and activated the powerful anti-zerg weapon, the Psi Disrupter, despite interference from Kerrigan's enigmatic minion, Samir Duran. Using other technologies, the UED took control of the second Overmind, turning most zerg to their side, while the Disrupter weakened Kerrigan's control over her own forces. Kerrigan was left in a weak position and resolved to strengthen her side by striking an uneasy alliance with Jim Raynor and Arcturus Mengsk. After the alliance severely weakened the UED Kerrigan betrayed them, then she turned her attention to the protoss. With assistance from Samir Duran she kidnapped the Dark Templar Raszagal and forced Zeratul to slay the second Overmind for her. Now in charge of all the zerg broods, she was suddenly abandoned by Duran.

Duran worked on a mysterious protoss/zerg hybridization project which Zeratul discovered. Meanwhile the protoss, UED and Terran Dominion all converged on Kerrigan but she was able to defeat them. After the Brood War the zerg remained on worlds they had already infested,sending out forces to explore and exploit various worlds and assimilate new species, and refrained from engaging in overt hostile actions against the terrans and protoss for four years. No expeditions sent to Swarm-controlled worlds have come back alive.
Four years after the Brood War the Swarm invaded Dominion space as a whole, focusing on the Core Worlds
Click here for better look

This picture above is the Zerg building and what untis they will produce.

Hatchery is the zerg main base. Can be upgraded to the Lair and Hive. Serves as the location where larva spawn and where the queen can be constructed.

Lair is tier two hatchery. Offers upgrades to Overseer (increased armor) and Overlord (increased armor and speed).

Hive is Tier three Hatchery. Necessary for unlocking all build and upgrade options.

Zerg is the only one with and upgradeable main base.

Spawning pools is a building that produce Zerglings and offers Zergling upgrades (increased movement speed).

Extractor are built on vespene gas deposits to make them accessible for mining.

Evolution Chamber use for research upgrades for burrow (unlocks burrow), slime (Overlord), generate creep (Overlord – this ability also increases Zerg buildings' creep generation speed), and lets you upgrade the queen's creep tumors to shriekers.

Roach Den enables the spawning of roaches, and contains roach upgrades (increased attack and armor ).

Nest lets zerglings morph into Banelings, contains Baneling upgrades (increased weapons and armor).

Hydralisk Den enables the spawning of Hydralisks, contains Hydralisk upgrades (increased attack and armor), can mutate into a deep warren. Once a deep warren is created, you can access a Lurker upgrade (increased weapons and armor).

Spire allows for the spawning of Mutalisks and Corruptors. Contains Mutalisk upgrades (increased weapons and armor) and Corruptor upgrades (increase weapons and armor). Can be upgraded to a Greater Spire.

Greater Spire unlocks the Swarm Guardian and opens up Swarm Guardian upgrades (increased weapons and armor).

Nydus Warren enables the spawning of Infestors and Nydus Worms. Friendly units can use the Nydus Warren to instantly travel to any other Nydus Warren or Nydus Canal owned by that player. Also offers spell upgrades for Infestors.

Ultralisk cavern lets you create Ultralisks and offers Ultralisk upgrades (increased weapons and armor).

The next post will be taking about the units of the zerg