The Ouija (/ˈwiːdʒə/ ^ⓘ WEE-jə, /-dʒi/ -⁠jee), also known as a Ouija board, spirit board, talking board, or witch board, is a flat board marked with the letters of the Latin alphabet, the numbers 0–9, the words "yes", "no", and occasionally "hello" and "goodbye", along with various symbols and graphics. It uses a planchette (a 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, which is moved about the board to spell words. The name "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 the modern Ouija board at their camps in Ohio during 1886 with the intent of enabling faster communication with spirits. Following its commercial patent by businessman Elijah Bond being passed on 10 February 1891, 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 in Satanic practices, 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.

The popular belief that the word Ouija comes from the French (oui) and German (ja) words for yes is a misconception. In fact, the name was given from a word spelled out on the board when medium Helen Peters Nosworthy asked the board to name itself. When she asked what the word meant, the answer she found was "Good Luck".

One of the first mentions of the automatic writing method used in the Ouija board is found in China around 1100 AD, in historical documents of the Song dynasty. The method was known as fuji "planchette writing". The use of planchette writing as an ostensible means of necromancy and communion with the spirit-world continued, and, albeit under special rituals and supervisions, was a central practice of the Quanzhen School, until it was forbidden by the Qing dynasty.

As a part of the spiritualist movement, mediums began to employ various means for communication with the dead. Following the American Civil War in the United States, mediums did significant business in allegedly allowing survivors to contact lost relatives. Use of talking boards was so common by 1886 that news reported the phenomenon taking over the spiritualists' camps in Ohio. The Ouija was named in 1890 in Baltimore, Maryland by medium and spiritualist Helen Peters Nosworthy.

Charles Kennard, the founder of Kennard Novelty Company, claims to have invented the board with his business partner, Elijah Bond, who patented it with help from his sister-in-law, spiritualist and medium Helen Peters Nosworthy. The local patent office at first refused a patent. Bond and Nosworthy then traveled to Washington, D.C. where they were also denied a patent until the chief patent officer asked the board to spell out his name, which it allegedly did. In 1901, an employee of Bond, William Fuld, took over the talking board production under the name "Ouija".^{[failed verification]}