The most ancient and powerful race in the galaxy (or so they believe), the Protoss possess a highly structured society based on the preservation of their way of thinking. Highly intelligent and gifted with great psionic powers, they nevertheless suffer from a certain inflexibility that makes them extremely difficult to work with.
Originally the Protoss were divided into several warring tribes, but they were united by a single Protoss scholar/philosopher, Khas. He is apparently responsible for strengthening the psionic racial link that all Protoss share, and he developed the Khala, a strict religion, philosophy, and social structure. Under the Khala, the Protoss have mostly abandoned their tribal lines and divided into three castes: Khalai, artisans and inventors; Templar, warriors and explorers; and Judicator, administrators and leaders.
Protoss technology is highly advanced compared to Terrans. It relies heavily upon warp technology - the ability to warp-in structures and unit by opening wormholes in the space-time continuum and bringing the materials directly in from the Home world. This makes the Protss very versatile as they don't need heavy machinery to construct everything, but bring in pre-fab structures from another location.
Mobile units, both air and ground are treated the same way. The wormhole is opened and it allows the units to pass through.