Conspiracy theory is any way of trying to understand or explain something or something, having as a principle that its nature is secret and part of a conspiracy plan.
Conspiracy theories can be understood as an attempt to explain something that, until then, has no explanation. Usually, they make references to important historical moments of humanity or events contemporaries who would be intertwined with the interests of powerful and Machiavellian conspirators, commanded by "secret societies", for example.
The main conspiracy theories existing in popular culture are related to secret societies, propagating stories that claim to be these organizations set up to control the world government, controlled by extraterrestrial beings, humans with paranormal powers and etc.
Theories claim that these secret groups are commanding the entire planet and the life that inhabits it, through various ways, such as subliminal messages, for example.
Learn more about the meaning of Subliminal message.
There are numerous conspiracy theories around the world and, with the advent of the internet, this information has become even more massive and "creative".
Conspiracy theories, also known as conspiracyism, attempt to "explain" almost every event in humanity since the existence of the Illuminati - a secret group that aims to take over the world, to the idea that Michael Jackson is still alive.
From a critical point of view, conspiracy theories are often discredited and ridiculed, due to the lack of concrete and scientific evidence on the matter at hand.
See also the meaning of Illuminati.