The tarot is a set of cards displaying allegorical representations. Originally used as playing cards, they later came to be used for divination.
Some traditions in mysticism and parapsychology hold that tarot cards can be used for divination or for accessing the unconscious. The cards are typically shuffled as a deck and laid out in one of a variety of patterns, often called "spreads", and then interpreted as a way of revealing facts about the subject of the reading. These might include the subject's thoughts and desires (known or unknown), or events that have taken place in their past or present or might take place in their future. Sometimes the subject must personally shuffle or deal the cards in order to affect the ordering.
Each card in the tarot deck has a variety of symbolic meanings that have evolved over the years, and many custom or themed tarot decks exist. The minor arcana cards have astrological attributions that can be used as general indicators of timing in the year, based on the Octavian calendar, and the court cards may signify different people in a tarot reading, with each suit's "nature" providing hints about that person's attitudes and physical and emotional characteristics.
Some schools of occult thought or symbolic study, such as the Hermetic Order of the Golden Dawn, consider the tarot to function as a textbook and mnemonic device for their teachings. This may be one cause of the word arcana being used to describe the two sections of the tarot deck: arcana is the plural form of the Latin word arcanum, meaning "closed" or "secret."
Recommended books (Free download):
Michael Prescott - Darklore
Robert Wang - The Qabalistic Tarot
John White - Toward Homo Noeticus
William Lammey - Karmic Tarot
