Scientology is a set of beliefs and practices invented by the American author L. Ron Hubbard, and an associated movement. It is variously defined as a cult, a business, a religion, a scam, or a new religious movement. Hubbard initially developed a set of ideas that he called Dianetics, which he represented as a form of therapy. An organization that he established in 1950 to promote it went bankrupt, and Hubbard lost the rights to his book Dianetics in 1952. He then recharacterized his ideas as a religion, likely for tax purposes, and renamed them Scientology. By 1954, he had regained the rights to Dianetics and founded the Church of Scientology, which remains the largest organization promoting Scientology. There are practitioners independent of the Church, in what is referred to as the Free Zone. Estimates put the number of Scientologists at under 40,000 worldwide.

Key Scientology beliefs include reincarnation, and that traumatic events cause subconscious command-like recordings in the mind (termed "engrams") that can be removed only through an activity called "auditing". A fee is charged for each session of "auditing".