Stargate

The stargate is an advanced protoss structure.

Overview
The stargate is one of the most technologically advanced of protoss facilities. It provides a warp link strong enough to call ships to a planet's surface. A large amount of electric (or similar) energy is generated just prior to the ship being warped in, showing itself visibly.

The warships of the protoss fleet require a much stronger warp link in order to materialize than a standard gateway can provide. The immense stargate is capable of calling ships from high orbit or across immense distances to appear on a planet surface. The construction of one or more stargates at a protoss base is a sure sign that it has become a major staging point for an offensive.

StarCraft
The stargate is the production building for protoss combat air units. Although it is a floating structure in the concept, it requires an area to construct and ground units cannot go underneath it.

Development
In the StarCraft beta, the stargate was originally known as the nexus.

StarCraft II
Stargates function exactly the same in StarCraft II.

When a stargate summons a unit, a shimmering silhouette of that unit appears within the stargate.

Stargates haven't been used by protoss players much over the course of Wings of Liberty, but Blizzard hopes to change this via the introduction of the tempest.

Development
New animations were developed for the stargate, which would reflect the unit being summoned.