A Soul is the incorporeal manifestation of the spirit, mind and life force of any living thing. Souls naturally radiate Essence, neither of which can be viewed by the naked eye.
Every living being possesses a Soul. This includes humans, guardian spirits, animals and even plants. Souls are the spiritual nature and embodiment of an individual's mind, personality and abilities that radiate Essence, a substance that bears in it qualities of the Soul from which they radiate. Essence can vary in size, color and radiance depending on the individual.
Souls and the Essence they give off play an important role in determining compatibility between two or more individuals. They aid in determining if two or more individuals can have a strong connection with each other if their Souls and Essences can connect well and maintain a harmonic state. If the Essence of two Souls can attune well with each other, then their compatibility will be strong whereas if the Essence of two Souls cannot attune well with each other, then their compatibility will be weak and fractured.
Souls are separated from their bodies after the death of an individual's physical body. The separation is not immediate, but rather a slow process that takes place over a long period of time. Essentially, after death, a Soul remains bound to a body by a faint, invisible bond. As time passes, this bond becomes longer and weaker, at which point decomposition begins to set in. After this, the Soul permanently separates from the body and its fate is unknown. However, before this occurs, an individual could be resurrected by the power of a guardian spirit, an act which forcibly rebinds the wayward Soul to its original body while restoring that body to a healthy state suitable for living. The shock and trauma of this act is great - causing a great amount of physical pain - and can have disastrous effects on the individual's psyche the longer the Soul has been separated from the body.
Souls can also be forcibly removed from an individual's body, though this will not kill them and only render them a lifeless husk until their Soul is returned. This is not an easy task to accomplish and requires something very powerful to forcibly remove a Soul. Souls can also be bound to other living things and even objects, which, like Soul removal, requires great power to accomplish and an equally powerful force to reverse.