T'au Empire - Castes: The T'au employ a caste-based social system that places the good of the many over the good of the few or the individual. In T'au culture, every person is viewed as an essential part of the whole society, though no individual is ever considered more important than the needs of the rest of society.Social standing is judged primarily by a being's standing within a caste of the T'au, with the suffix 'la designating the lowest rank in the caste (shas'la: Fire Warrior, fio'la: Earth Worker, por'la: Water Bureaucrat) and the suffix 'o designating the highest (shas'o: Fire Commander, fio'o: Earth Planner, por'o: Water Ambassador). The five castes of the T'au are as follows:Fire Caste (Shas) -- The Fire Caste composes the bulk of the ground military of the T'au Empire, and as such are the T'au most often encountered by the Imperium. They average as tall as or slightly shorter than an average Human, and are generally muscular. This comes from the Fire Caste's origin on the plains of T'au, the T'au homeworld, where they survived as hunters and warriors. T'au from the world of Vior'la tend to have slightly greater muscle mass than is common among their species because of the increased gravity of Vior'la.Earth Caste (Fio) -- The Earth Caste is composed not only of the T'au's labourers and technicians, but also artisans, scientists and engineers. They are usually credited with the significant leaps in technology that the T'au Empire has enjoyed. The members of the Earth Caste form the foundations upon which the T'au Empire is built. The inhabitants of this caste are generally short and stout of build.Water Caste (Por) -- The Water Caste is primarily composed of T'au merchants and diplomats. They are tasked with seeking and maintaining diplomatic relations with the other member species of the T'au Empire, as well as maintaining the ease of communication and cooperation between the other castes. The Water Caste are generally taller and slimmer than other T'au, and favor diplomatic training and social grace over confrontation or combat. They are more capable in communicating in the languages of other intelligent species than most other T'au. From the time when the T'au discovered the existence of the Imperium, there are several accounts where Water Caste ambassadors were dispatched to Imperial worlds, and those worlds accepted the Greater Good without a fight to become new T'au septs.Air Caste (Kor) -- The Air Caste of the T'au function not only as messengers, but also as the bulk of the T'au Protection Fleet and the T'au Merchant Fleet. The T'au of the Air Caste are even taller and more slender than the Water Caste, with long, skinny appendages and hollow bones. These traits are attributed to their lives lived mostly in low to zero-gravity voidships and void stations. This is exacerbated by Air Caste reluctance, if not outright refusal, to land on planets, as their skeletons have atrophied to the point where injury and broken bones are commonplace when they spend time in a gravity well. In the past, during the time of the Mont'au before the unification of the T'au tribes, the Air Caste had membranes stretching between their limbs, which allowed them to glide on air currents. T'au Air Caste pilots are recognised as generally superior to Human pilots due to their better fighter craft, though they lack a normal Imperial pilot's level of combat experience.Ethereal Caste (Aun) -- The Ethereals are the political and religious leaders of the T'au. They resemble the Fire and Water Castes physically, but are marked by a diamond-shaped ridge of raised bone in the centre of their foreheads. Their origins are unknown, and most T'au will never refuse a request made by an Ethereal. They are sometimes also found on the battlefield, but whether as leaders or observers remains to be seen. The leader of the Ethereal Caste is a T'au named Aun'Va, the Ethereal Supreme and Master of the Undying Spirit who chaired the Ethereal High Council and served as the head of state or Aun'o of the T'au Empire.