The gulag system of North Korea exists in a strange world between secret and unsecret. No one knows for sure how many thousands or millions of people are locked away in the camps, which officially do not exist, and information about what goes on there can be sparse. But we can watch the camps grow and contract from satellites, where they're so plainly and publicly visible they're labeled on Google Maps, and we are learning more all the time from the trickle of defectors and escapees who make it out of the Hermit Kingdom.

Here is a guide to the basics of North Korea's infamous labor camps: how they work, who is sent away, and why these monstrous abuses of human rights continue.

North Korea's gulag system: the basics

North Korea operates four enormous labor camps for political prisoners — sprawling, city-sized facilities in the country's frigid and mountainous north. Most inmates are sent for life as punishment for minor slights, or because a relative committed some offense. They are subjected to backbreaking labor, routine torture and starvation, constant fear of arbitrary execution, and conditions so squalid most do not survive past age 45.

These gulag camps — which are separate from the country's more conventional prison systems — are thought to house 100,000 or more people, including many women and children. Often, entire families are sent away for one member's offense, through two or three generations. Sometimes inmates will have no idea why they're there, or will have never met the relative for whom they are punished with a life of torture and malnutrition.

What makes them the worst human rights abuses on earth

A United Nations report called the camps a human rights abuse "without any parallel in the contemporary world." Being sent to the camps is a death sentence, one that can take several torturous years or decades to carry out. The torments of the gulag are in many ways a more severe microcosm of North Korea outside of the camps.

Inmates are given not quite enough food to survive, forcing them to turn against one another — or curry favor somehow with the guards — to secure enough to eat. They are assigned brutally punishing work, such as coal mining without proper equipment or ventilation. Women and girls are subject to rape and molestation by guards.

Because the generations-long sentences mean that something akin to families often form in the camps, inmates live with the fear that they will be tortured or killed for a family member's crime — and are often forced to betray their own family to survive. And all inmates, from young children up to pregnant mothers, live with the constant fear of arbitrary execution, because they gave offense, or dropped a piece of equipment, or for no reason at all.

Why this is happening: to control by fear

The camps are an extension of North Korea's totalitarian police state, meant to exert total control and instill complete obedience. That police state begins in homes, every one of which is required to hang portraits of leader Kim Jong Un and is outfitted by a radio — impossible to turn off — that blasts state propaganda. Neighborhoods and housing blocks are assigned formal political officers, usually male, and informal political monitors, usually female, who inform on the slightest breach.

Underlying it all is the threat of the gulag: a fate worse than simple death by execution or starvation. The camps are meant to terrify North Koreans into not just compliance but active collaboration, informing on neighbors and family members. This is paired with nationalistic propaganda meant to instill a worshipful love of the state and of leader Kim Jong Un.

The camps also play an economic role, as sources of mining, logging, and agriculture.

What can the world do about it: hope for collapse

There is very little that the world can do, or is willing to do, to end the camps. The North Korean government has successfully distracted the world with its nuclear weapons program and its random-seeming threats and acts of provocation; it knows that the world cares much more about deterring a North Korean attack than about ending the gulag system.

This is one major reason why North Korea periodically alternates between engaging in nuclear negotiations and blustering provocations. This keeps the global focus on nukes, and not on North Korea's internal human rights abuses, which it sees as crucial for maintaining control.

There is zero indication that the Kim family, which has ruled for three generations, will ever soften or reform these abuses. Nor is there any chance that the outside world will force them to stop: North Korea's nuclear deterrent makes that impossible. Perversely, the "best" we can hope for is that the government collapses or is overthrown from within, which would no doubt be catastrophic, but could at least mean the end of the cruelest system of human rights abuses in the world.

Correction: This article originally stated that North Korea operates six gulag camps. In fact, as Curtis Melvin of the US-Korea Institute points out, North Korea has recently closed Camps 18 and 22 as part of its apparent consolidation of prisoners into other camps, meaning it currently operates four. Thanks to Curtis for pointing this out.