The ouija ( WEE-jə, -⁠jee), also known as a spirit board or talking board, is a flat board marked with the letters of the Latin alphabet, the numbers 0–9, the words "yes", "no", occasionally "hello" and "goodbye", along with various symbols and graphics. It uses a planchette (small heart-shaped piece of wood or plastic) as a movable indicator to spell out messages during a séance. Participants place their fingers on the planchette, and it is moved about the board to spell out words. "Ouija" is a trademark of Hasbro (inherited from Parker Brothers), but is often used generically to refer to any talking board.

Spiritualists in the United States believed that the dead were able to contact the living and reportedly used a talking board very similar to a modern Ouija board at their camps in the U.S. state of Ohio in 1886 to ostensibly enable faster communication with spirits. Following its commercial introduction by businessman Elijah Bond on 1 July 1890, the Ouija board was regarded as an innocent parlor game unrelated to the occult until American spiritualist Pearl Curran popularized its use as a divining tool during World War I.

Paranormal and supernatural beliefs associated with Ouija have been criticized by the scientific community and are characterized as pseudoscience. The action of the board can be most easily explained by unconscious movements of those controlling the pointer, a psychophysiological phenomenon known as the ideomotor effect.

Mainstream Christian denominations, including Catholicism, have warned against the use of Ouija boards, considering their use Satanic practice, while other religious groups hold that they can lead to demonic possession. Occultists, on the other hand, are divided on the issue, with some claiming it can be a tool for positive transformation, while others reiterate the warnings of many Christians and caution "inexperienced users" against it.