Looking at the Protoss Starcraft 2 Tech Tree  | read this item

Nearly every unit in Starcraft 2 has a different set of requirements to utilize it effectively in combat.  Knowing your Protoss Tech Tree can help you get your best units on the field as soon as possible.  Today we’re going to take a look at the the requries for all the buildings and in the Protoss player’s arsenal.

The Nexus

Every race starts with a base.  In the Protoss case, it is the Nexus.  The first is always provided to the player along with a handful of Probes to start their harvesting process.    The Nexus serves at the core requirement of every building that can be built with the exception of an Assimilator and a Pylon.  From the Nexus, Probes and Motherships are produced and the Gateway and Forge buildings become unlocked.  In addition, the Nexus has the ability to “Chrono-boost” any production building, reducing its build/research time.

The Pylon

This building is a core of construction for all Protoss buildings except for the Nexus and the Assimilator.  Its function mirrors the function of Zerg creep however, a Pylon may be destroyed, immediately shutting down any buildings for which it was the sole source of power.  It is always advisable to make sure that building at powered by multiple Pylons when able.

The Assimlator

This is a harvesting building that produces Vespene Gas from a Vespene Geyser for probes to collect.  It must be built on top of a Vespene Geyser.  The optimal harvest rate uses three Probes dedicated to gathering from the facility.

The Forge

This building is the core of all ground unit upgrades along with the Plasma Shield upgrade that affects all units.  While the Forge doesn’t build units on its own, it does unlock the Photon Cannon for construction.

The Gateway

This building produces all Protoss ground combat units.  It requires a Nexus to be present under the player’s control to be built in addition to requiring the constant presence of a Pylon’s Power Field to be built and to continue to operate. In addition to producing units, it unlocks access to the Cybernetics Core.  The Gateway also has the ability to transform into a Warpgate, allowing this building to send units directly to any of the player’s Pylons on the battlefield.

The Cybernetics Core

The building contains the base unit upgrades for all air units in addition to the Hallucination and Warpgate upgrades.  This building requires the a Pylon’s Power Field and a Gateway or Warpgate under the player’s control in order to be built.  The Cybernetics Core also unlocks the Stalker and Sentry units to be produced at a Gateway or Warpgate as will as unlocks the Stargate, the Twilight Council, and the Robotics Facility for construction.

The Stargate

This building is a production facility that produces the Carrier, the Phoenix, and the Void Ray.  This building requires the presence of a Pylon’s Power Field as well as a Cybernetics Core in order to be built.  This building also unlocks the Fleet Beacon for construction.

The Twilight Council

This build is an upgrade facility containing the unit upgrades of Charge for the Zealot and Blink for the Stalker.  A Pylong’s Power Field as well as a Cybernetics Core is required in order to be constructed.  The Dark Shrine and Templar Archives are unlocked as long as this building remains under the player’s control.

The Robotics Facility

This building is a production facility that produces the Colossus, the Immortal, the Warp Prism and the Observer.  A Pylon’s Power Field as well as a Cybernetics Core are required in order to be constructed.  The Robotics Bay is also unlocked as long as this building remains under the player’s control.

The Fleet Beacon

This building is an upgrade facility containing the unit upgrades of Flux Vanes for the Void Ray and Graviton Catapult for the Carrier.  A Pylon’s Power Field as well as a Stargate are required in order to be constructed.  The Fleet Beacon unlocks the Carrier to be produced at a Stargate as well as a Mothership to be constructed at a Nexus.

The Dark Shrine

This building is a pure tech facility that unlocks the Dark Templar to be produced by a Gateway or Warpgate.  A Pylon’s Power Field as well as a Twilight Council are required in order to be constructed.

The Templar Archives

This building is an upgrade facility containing the unit upgrades of Psionic Storm and Khaydarin Amulet for the High Templar.  A Pylon’s Power Field as well as a Twilight Council are required in order to be constructed.   This building also unlocks the High Templar to be produced by a Gateway or Warpgate.

The Robotics Bay

This building is an upgrade facility containing the unit upgrades of Extended Thermal Lance for the Colossus, the Gravitic Booster for the Observer, and the Gravitic Drive for the Warp Prism.  A Pylon’s Power Field as well as a Robotics Facility are required in order to be constructed.  This building also unlocks the Colossus to be produced at a Robotics Facility.

Those are all the buildings a Protoss Player can produce.  You can see the tech relation as well as bit of information concerning what they can do.