Pylon

This is the Protoss structure that creates Supply. It also powers their Structures, and Units can be Warped in near them with the use of a Warp Gate.

Overview
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100 25 +8 A Pylon is a Protoss structure needed for a Probe to be able to warp in most Protoss buildings (other Pylons, Nexus, and Assimilators being the exceptions). It's also the Supply structure for the Protoss, increasing available Psi. Pylons generate a short-ranged aura of energy, which can provide the power needed by structures and Warp Gates. A forward Pylon used for Warping in Units is referred to as a proxy Pylon.

You Must Construct Additional Pylons
If a player attempts to create a Unit when they don't have enough Psi, they will hear an error message from the Protoss advisor; "You must construct additional Pylons". This phrase has grown into a popular meme, almost as famous as Starcraft itself. Said advisor can be seen here in the Carbot Animations Starcrafts series, harassing his Probes.