Conspiracy theories propose secret plots by powerful groups and rely on three key principles - nothing happens by accident, things are not always as they seem, and everything is connected. People are drawn to conspiracy theories for reasons like maintaining a positive self-image and desire for understanding and control. Common biases that fuel belief in conspiracies include confirmation bias and proportionality bias. Two well-known conspiracy theories discussed in the document are that Princess Diana's death was staged and the flat earth theory that photos of a round earth are fake.