Simulacra and Simulation (French: Simulacres et Simulation) is a 1981 philosophical treatise by Jean Baudrillard seeking to interrogate the relationship among reality, symbols, and society.

Simulacra are copies that depict things that either had no reality to begin with, or that no longer have an original.^[1] Simulation is the imitation of the operation of a real-world process or system over time.^[2]

...The simulacrum is never that which conceals the truth—it is the truth which conceals that there is none. The simulacrum is true.^[3]

Simulacra and Simulation is most known for its discussion of symbols, signs, and how they relate to contemporaneity (simultaneous existences). Baudrillard claims that our current society has replaced all reality and meaning with symbols and signs, and that human experience is of a simulation of reality. Moreover, these simulacra are not merely mediations of reality, nor even deceptive mediations of reality; they are not based in a reality nor do they hide a reality, they simply hide that anything like reality is relevant to our current understanding of our lives. The simulacra that Baudrillard refers to are the significations and symbolism of culture and media that construct perceived reality, the acquired understanding by which our lives and shared existence is and are rendered legible; Baudrillard believed that society has become so saturated with these simulacra and our lives so saturated with the constructs of society that all meaning was being rendered meaningless by being infinitely mutable. Baudrillard called this phenomenon the "precession of simulacra".

"Simulacra and Simulation" breaks the sign-order into 4 stages:

1. The first stage is a faithful image/copy, where we believe, and it may even be correct, that a sign is a "reflection of a profound reality" (pg 6), this is a good appearance, in what Baudrillard called "the sacramental order".
2. The second stage is perversion of reality, this is where we come to believe the sign to be an unfaithful copy, which "masks and denatures" reality as an "evil appearance—it is of the order of maleficence". Here, signs and images do not faithfully reveal reality to us, but can hint at the existence of an obscure reality which the sign itself is incapable of encapsulating.
3. The third stage masks the absence of a profound reality, where the simulacrum pretends to be a faithful copy, but it is a copy with no original. Signs and images claim to represent something real, but no representation is taking place and arbitrary images are merely suggested as things which they have no relationship to. Baudrillard calls this the "order of sorcery", a regime of semantic algebra where all human meaning is conjured artificially to appear as a reference to the (increasingly) hermetic truth.
4. The fourth stage is pure simulation, in which the simulacrum has no relationship to any reality whatsoever. Here, signs merely reflect other signs and any claim to reality on the part of images or signs is only of the order of other such claims. This is a regime of total equivalency, where cultural products need no longer even pretend to be real in a naïve sense, because the experiences of consumers' lives are so predominantly artificial that even claims to reality are expected to be phrased in artificial, "hyperreal" terms. Any naïve pretension to reality as such is perceived as bereft of critical self-awareness, and thus as oversentimental.