A type of ritual where a group of people known as “sitters” get together with a person (the “medium”) who has powers to communicate with non-physical entities for the purpose of communicating with spirits, usually of the dead. Also known in some areas as a “sitting” or a “circle.”
Although there is a long history of this sort of activity, it became popular in the West in the mid-19th century as part of a religion known as Spiritualism or Spiritism. Many occultists of the period were involved with this movement, and some occult groups looked askance at it. Two fake spiritualists, Mr. and Mrs. “Horos,” tricked the head of the Hermetic Order of the Golden Dawn, into believing in them, and this episode ended up making the Golden Dawn public in an embarrassing way.
After the massive deaths of WWI and the flu epidemic that followed, the desire to contact the dead achieved a fever pitch. Many scientists in other fields were involved, as was Sir Arthur Conan Doyle and possibly Abraham Lincoln.
Whenever such an interest grows, there are people who take advantage of it, and the history of séances and Spiritualism, unfortunately, has many darker and fraudulent markers. When the famous magician Houdini needed to put some fire under his flagging career, he started exposing fake mediums, a practice some conjurors continue to this day.
Spiritualism and the séance are still practiced today, albeit in smaller numbers. Many of the practices were absorbed into New Thought, the New Age movement, and various occult traditions and orders.