Spirit (Being)
Spirits are disembodied entities that originate in, and usually dwell in, the Umbra - for that reason, some mages call them the "Umbrood".
These beings are primarily encountered by Garou (aka werewolves) and certain types of mages, although numerous other supernatural beings are capable of discerning or even interacting with the spirit world. Mages use the term Umbrood as an umbrella term for spirits, to minimize confusion with the Sphere of Awakened magic that is also called Spirit. Wraiths and demons are among the more specialized types of spirits, and many references to "spirits" specifically do not include these two types of beings.
Nature
Spirits usually only have the traits of Rage, Gnosis, and Willpower; they do not normally possess Attributes or Abilities. However, many Umbrood spirits and demons are exceptions to this rule. Spirits possess distinctive and sometimes unique powers called Charms, which have effects based on the spirit's nature. For example, elementals can create whatever element they embody and can blast opponents with their element in combat, and the bane-spirits that serve the malefic Wyrm have powers of corruption, suffering, and decay.
Some spirits can use the Materialize charm, which allows them to cross the Penumbra into the material world for a time; spirits usually manifest predetermined ratings in their Attributes and Abilities while materialized. Other spirits can cross over permanently by binding themselves to a mortal (or rarely an animal, object, or place) via the Possession charm. The resulting mortal-spirit hybrid becomes one of four known types of Possessed: fomori, which serve the destructive and corrupt Wyrm; drones, which serve the stifling, static Weaver; gorgons, which serve the chaotic and generative Wyld; and the rare kami, which serve Gaia, the spirit of the Earth itself.
Social Environment
Spirits, at least the sapient ones, are social creatures. They interact, they organize, and they plan. They have friends, or they at least play favorites. They hold rivalries and grudges. Each spirit is its own individual, even if they’re bound to certain aspects tied to their nature. In the Umbra, no one lives in a vacuum.
Just as there’s no place in the physical world that’s completely one thing, there’s no section of the Umbra that’s only spirits of envy or lightning. In a reflection of a pasture, animal spirits exert their influence on their physical reflections and re-enact the cycle of predator and prey. They negotiate with the spirit of a nearby stream to ensure their charges are nourished. They work with the field spirit to coax a passing wind spirit to send a breeze to spread grass seeds to a new patch of land. Add in spirits that are reflections of concepts, and the landscape diversifies. Hunting spirits watch the predations of animal spirits with glee. An emissary of Helios dries out another patch of land just in time for the breeze to spread more seeds to it. These 'ecosystems' of spirits are known as courts: semi-enclosed spaces where the intricate hierarchies of the Umbra play out in miniature, often serving as a reflection of the area's physical counterpart.
Some spirits are also parts of 'broods': Minor spirits existing under the protection and guidance of their 'parent' spirit in exchange for servitude. For instance, one may encounter individual spirits of rock and stone inhabiting the Umbral reflection of a mountain or cave, but those lesser spirits are part of the brood of the Incarna of Stone itself, the 'parent' and patron of those minor spirits. Spirits can also join the brood of an unrelated spirit through more understandable politicking, such as Mammoth joining Griffin's brood for the sake of its own survival, rather than that being the ordained way of things for the two of them.