Pylon

A Pylon is a Protoss structure needed for a Probe to be able to warp in most Protoss buildings (other Pylons, Nexuses and Assimilators being the exceptions). Protoss structures and units, to a lesser extent, draw their energy from a great psionic energy matrix that emanates from Aiur. While a Nexus provides a link to this matrix, Khaydarin Crystal-based Pylons are needed to actually tap into the energy required to provide psionic energy to new colonies. Each Pylon generates a short-ranged aura of energy, which can provide the power needed by structures and warp gates. If a Protoss building loses its connection to the Psionic Matrix, it will shut down until it is reconnected, and new units cannot be gated in if there is insufficient psionic energy to provide them with power.

Pylon-Based Defenses
Large clusters of Pylons were once used to generate an electromagnetic field that prevented Zerg Spire units from maneuvering. The clusters were based at Talematros, capital of Shakuras, before Samir Duran's forces destroyed them.

StarCraft II
In StarCraft II, the Pylon is far less resilient than its predecessor. However, the Protoss can also use Phase Prisms to support the structures if a Pylon is lost.

The Pylon has its own portrait instead of using the protoss racial portrait like other buildings.

Upgrades

 * Plasma Shields