Spiritism is a religion, self-described as a spiritualistic philosophy, that started in the 19th century by the French educator Hippolyte Léon Denizard Rivail, who, under the pen name Allan Kardec, wrote books on "the nature, origin, and destiny of spirits, and their relation with the corporeal world". Spiritists refer to Kardec as the codifier.

Spiritist philosophy postulates that humans, along with all other living beings, are essentially immortal spirits that temporarily inhabit physical bodies for several necessary incarnations to attain moral and intellectual improvement. It also asserts that disembodied spirits, through passive or active mediumship, may have beneficent or malevolent influence on the physical world. Spiritism is an evolution-affirming religion.

The term first appeared in Kardec's book, The Spirits Book, which sought to distinguish Spiritism from spiritualism.

Spiritism is currently represented in 35 countries by the International Spiritist Council. It has influenced a social movement of healing centers, charity institutions and hospitals involving millions of people in dozens of countries, with the greatest number of adherents in Brazil. Spiritism is a major component of the syncretic Afro-Brazilian religion Umbanda and also very influential in Cao Đài, a Vietnamese religion started in 1926 by three spirit mediums who claimed to have received messages that identified Allan Kardec as a prophet of a new universal religion.

Source: Wikipedia