Spiritualism is a dualist metaphysical belief that the world is made up of at least two fundamental substances, matter and spirit. This very broad metaphysical distinction is further developed into many and various forms by the inclusion of details about what spiritual entities exist such as a soul, the afterlife, spirits of the dead, deities and mediums; as well as details about the nature of the relationship between spirit and matter. It may also refer to the philosophy, doctrine, or religion pertaining to a spiritual aspect of existence.