A Guide to the Creepy Human "Sleeves" and Other Crazy Terms in 'Altered Carbon'

altered carbon netflix

Altered Carbon, Netflix’s new cyberpunk drama series, feels familiar. The setting -- a velvet-dark future city, formerly San Francisco, with pops of neon light -- is reminiscent of Blade Runner, that other hardboiled future world where the limitations of mankind are tested as technology criss-crosses the boundaries of morality. In Blade Runner, humanity is forever altered with the development of replicants, genetically engineered androids that are virtually indistinguishable from biological human beings. But Altered Carbon, based on a 2002 novel by Richard K. Morgan, presents a more perilous dilemma. Instead of integrating society with human-like androids, this universe has found a way to prolong life by digitizing the soul.

But is consciousness really the soul? And if it’s digitized, what does that mean for physical bodies? Do they matter as much as we’ve been lead to believe, or are they really just shells of matter that hold no bearing on our actual selves?

These are the questions woven into Altered Carbon’s opulent tomorrow, and they carry through a 10-episode season that wrestles with a new reality. As seen through the horrified eyes of Takeshi Kovacs (Joel Kinnaman), a super-soldier once tasked with putting an end to the immoral tech that now runs rampant -- whose mind is resurrected and placed in a new body to help solve the "murder" of one of the oldest and richest men alive -- we're slowly introduced to the terrifying implications of a world where bodies are disposable and eternal life is only comfortable for those who can afford it.

Because it depicts a future that doesn't exist (yet!), the show throws a lot of tech and terminology at its audience right away, before jumping head-on into a complicated web of plot. To keep your head straight, here’s a brief guide to the important terms in Altered Carbon’s frightening world.

altered carbon netflix stacks

What are the "stacks" in Altered Carbon?

Those digitized souls we mentioned? Those are called "stacks" -- short for “cortical stack" -- which are implanted into biological humans when they're 1-year-old. Stacks contain the human mind and everything that comes with it, including memory and emotion. Stacks essentially make their owner immortal, as they can be endlessly re-uploaded into new bodies so long as the stack itself isn’t damaged.

As we learn, certain groups, like Catholics, resist cortical stacks so they can get into heaven, which is impossible if the soul never truly dies. Because of their beliefs, Catholics are targeted by criminals since they won’t be around to identify their assailant.

When a stack is permanently destroyed, it is referred to as "RD," or "real death."

What are the "sleeves" in Altered Carbon?

Human bodies are known as “sleeves” because they're merely casing for the stacks. As we quickly learn, the quality of your sleeves corresponds to your finances. The wealthy are able to afford the best-looking, strongest, healthiest sleeves, whereas the poor have to make due with whatever’s left, or opt for a synthetic body, which is considered the worst of the worst. In the pilot episode, we see a 7-year-old girl who died in a car crash returned to her parents in the body of an elderly woman, since that’s all they could afford. Because sleeves are still biological bodies, the stacks don’t always alter certain behaviors. Kovacs is in the sleeve of a heavy smoker, so he has to smoke, too. Psychasec is the company that developed the sleeve technology, and it sells them to the public, complete in creepy, giant plastic bags. 

There are limitations of sleeving, and ways to get around sleeving regulations. Multi-sleeving, for instance, refers to the illegal practice of downloading the contents of your stack into multiple sleeves. There’s also a process known as "spin up," where a stack is temporarily placed into a sleeve for interrogation purposes.

altered carbon envoys

Who are the Envoys?

These elite soldiers were imbued with "neuro-chems," which gave them heightened intuition and the ability to withstand the mental torture of the re-sleeving process. They also lack emotion, are able to detect human error, and have perfectly preserved memories. Basically, they’re perfect detectives. Koyacs was an Envoy in his past life, which is part of the reason Laurens Bancroft -- the rich man who resurrects him -- wants him to help decode his murder. (Bancroft’s wealth meant that he could afford to back up his stack in a cloud, so that even after it’s destroyed, he was able to come back.)

What are "meths"?

No, not methamphetamine. In this future world, wealthy people -- like Bancroft -- who are able to afford endless backups and sleeves are known as “meths.” This is a reference to Methusaleh, the Biblical figure who lived longest, with a lifespan of almost 1,000 years. Instead of riding out the lifespan of their sleeve, meths will jump into new, better bodies when their sleeves start to age, preserving themselves in eternal youth. They're despised by common folk who sneer at their privileged, immoral wealth.

What does "needlecasting" mean?

Interstellar travel is possible in Altered Carbon thanks to a process known as "needlecasting." Sleeves don’t physically travel to other planets and galaxies, but the coding in their stacks is beamed there and fitted to a different sleeve. Originally meant as a war tactic, the complications -- namely, that it takes a while to adjust to a sleeve, so soldiers were too disoriented to properly fight -- led to the development of Envoys.

Some of these terms are bound to throw off people who want to come into a show knowing exactly what to expect, but once you get a feel for the rhythm and language of Altered Carbon, the unfamiliar phrases become an essential part of the world.

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Lindsey Romain is a writer and editor living in Chicago. She covers politics for Teen Vogue and has also appeared in Vulture, Birth.Movies.Death, and more. Follow her on Twitter @lindseyromain.