The red pill and its opposite, the blue pill, are popular culture symbols representing the choice between embracing the sometimes painful truth of reality (red pill) and the blissful ignorance of illusion (blue pill). Redpills are people who have chosen to face reality, while bluepills remain living in ignorance of the truth, whether by choice or because they have not had a choice.

The terms, popularized in science fiction culture, are derived from the 1999 film The Matrix. In the film, the main character Neo is offered the choice between a red pill and a blue pill. The blue pill would allow him to remain in the fabricated reality of the Matrix, therefore living the "ignorance of illusion", while the red pill would lead to his escape from the Matrix and into the real world, therefore living the "truth of reality" even though it is a harsher, more difficult life. In The Matrix, Neo (Keanu Reeves) hears rumors of the Matrix and a mysterious man named Morpheus. Neo spends his nights at his home computer trying to discover the secret of the Matrix and what the Matrix is. Eventually, another hacker, Trinity (Carrie-Anne Moss), introduces Neo to Morpheus.

Morpheus (Laurence Fishburne) explains to Neo that the Matrix is an illusory world created to prevent humans from discovering that they are slaves to an external influence. Holding out a capsule on each of his palms, he describes the choice facing Neo: As narrated, the blue pill will allow the subject to remain in the fabricated reality of the Matrix; the red serves as a "location device" to locate the subject's body in the real world and to prepare him or her to be "unplugged" from the Matrix. Once one chooses the red or blue pill, the choice is irrevocable.

Neo takes the red pill and awakens in the real world, where he is forcibly ejected from the liquid-filled chamber in which he has been lying unconscious. After his rescue and convalescence aboard Morpheus' ship, Morpheus shows him the true nature of the Matrix: a detailed computer simulation of Earth at the end of the 20th century (the actual year, though not known for sure, is approximately two hundred years later). It has been created to keep the minds of humans docile while their bodies are stored in massive power plants, their body heat and bioelectricity consumed as power by the sentient machines that have enslaved them.