There have always been refugees: people who are forced from their home countries by conflict or repression or something else, and who must find new homes and new lives abroad. But there is something different about what's happening now. The world is experiencing a crisis more severe than anything it has seen in decades — and we are just beginning to wake up to what that means.

Make no mistake: The current refugee crisis is global. The coverage has focused heavily on the refugees arriving in Europe, and especially on Syrian refugees. But in fact refugees are fleeing countries from Honduras to Nigeria to Myanmar, and they are arriving in wealthy countries including the US and Australia, as well as poorer ones like Turkey and Lebanon. It is a worldwide problem — one whose scale and severity is unmatched since World War II.

What follows is a straightforward explanation of the very basics of the refugee crisis: the key facts you need to know to understand what's happening, how the crisis became so severe, and what can be done to fix it.

1) What is the refugee crisis?

At its most basic level, the refugee crisis is driven by a single fact: There are 19 million people in the world who are currently refugees — a disastrously high number — and they all need to find somewhere they can live in safety.

But when we talk about the global refugee crisis, we're not just talking about numbers. We're really talking about the ways in which nations fail refugees. That happens at four distinct stages — all of them terrible in their own way. All refugees go through at least one of those terrible steps, but the most vulnerable people, if they do ever manage to reach safety at all, are likely to go through all four.

The first step of the refugee crisis is the persecution that forces refugees to flee their homes in the first place. Some are fleeing war, some political persecution, and some other kinds of violence, but all refugees, by definition, experience this. Today Syria's civil war is especially dire. But it's not the only cause of the global refugee crisis, which is being driven by a host of national crises taking place around the globe, many of which are totally unconnected to one another. There are wars in Somalia and Afghanistan and Libya, lower-level violence in Central America and Nigeria and Pakistan, persecution in Eritrea and Myanmar and Bangladesh, and so on.

The second step is what happens to those refugees once they are forced out of their homes: Often, though not always, they end up in camps. Life in the camps is often difficult, cramped, and unsafe, with few prospects for work or education. This is a crisis for the refugees as well for as the countries that house them; for instance, host countries like Lebanon and Turkey are struggling to manage their camps for refugees and to absorb the thousands or even millions of people who live in them. These camps are a global failure: The UN is far short of the $8.4 billion it says it needs to provide bare minimum services just for Syrian refugees. And they are also national failures: They keep refugees from integrating into the local communities and creating stable, productive new lives there. At their worst, camps can keep families stuck in limbo for generations.

The third step is what happens when refugee families, perhaps after seeing that the camps offer them little hope or protection, seek out safety from persecution further afield, often in developed countries, particularly in Europe. The journey is often horrifyingly dangerous: Many families drown crossing the Mediterranean in rickety boats, for example, which is why a Syrian toddler's body washed up on a Turkish beach last week. The families understand the risk, and may pay thousands of dollars per person for the trip, but often feel it is their only option. The trip is so perilous in part because Western governments, wanting to discourage all forms of uncontrolled migration, have let it be that way as a matter of deliberate policy.

The fourth step is the one that many Western countries are experiencing now: what happens when large numbers of refugees show up. Often, they face systems that are badly broken — the squalid overcrowded camps in Greece, for example — or that are overtly hostile to refugees in an effort to keep them out. This is changing a little bit, but most European countries are still trying to keep refugees out and refusing to accept even a remotely sufficient number of them for resettlement, which means the families who make it to Europe end up in camps, sleeping in train stations, or living in fear of deportation.

This last step of the crisis is about much more than just funding: It's forcing some really sensitive political issues to the surface in Europe, over migration and identity and the future of the European Union. Until Europeans can figure out those issues, hundreds of thousands of refugees will continue to suffer.

2) Why are there so many refugees right now?

There's no single reason, because a number of the crises driving people from their homes are not connected. There's no real link, for example, between the war in Afghanistan and the persecution of the Rohingya minority in Myanmar, or between violence in Nigeria and violence in Honduras and El Salvador.

But there is one thing that jump-started the crisis, and that has helped to make it so especially bad: the Arab Spring. It began in 2011 as a series of peaceful, pro-democracy movements across the Middle East, but it led to terrible wars in Libya and Syria. Those wars are now helping to fuel the refugee crisis.

It's not hard to understand why Syrians are fleeing. Bashar al-Assad's regime has targeted civilians ruthlessly, including with chemical weapons and barrel bombs; ISIS has subjected Syrians to murder, torture, crucifixion, sexual slavery, and other appalling atrocities; and other groups such as Jabhat al-Nusra have tortured and killed civilians as well. The civil war has killed a shocking 250,000 people, displaced half of the population, and caused one in five Syrians (4 million people) to flee the country.

Libya's role in the refugee crisis is different: The war there is terrible, but it has not displaced nearly as many people. What it has done, however, is open up a long-closed route from Africa to Europe.

For years, the EU kept refugees out of sight and out of mind by paying Libyan dictator Moammar Gadhafi's government to intercept and turn back migrants that were heading for Europe. Gadhafi was something like Europe's bouncer, helping to bar refugees and other migrants from across Africa. His methods were terrible: Libya imprisoned migrants in camps where rape and torture were widespread. But Europe was happy to have someone else worrying about the problem.

When Libya's uprising and Western airstrikes ousted Gadhafi in 2011, Libya collapsed into chaos. The route through Libya — and, from there, across the Mediterranean — suddenly opened, though it remained dangerous. As a result, the number of people making the perilous journey to Europe climbed considerably.

There is another reason that this crisis is so severe: Politics within Europe are unusually hostile to refugees and migrants at the moment. That isn't causing the numbers of refugees to actually increase, of course, but it's part of why the refugees are in crisis, stuck in camps or dying in the Mediterranean rather than resettling safely in Europe. There are a few reasons anti-refugee and anti-migrant politics are rising in Europe (more on this below), but it's making it harder for Europe to deal with the crisis, and many refugee families are suffering as a result.

3) Why is there a war in Syria, and why is it so terrible?

Here, from Zack Beauchamp, is the briefest, simplest way we can describe this complex, horrific war:

Syria is a relatively new country: Its borders were constructed by European powers in the 1920s, mashing together several ethnic and religious groups. Since late 1970, a family from one of those smaller groups — the Assads, who are Shia Alawites — has ruled the country in a brutal dictatorship. Bashar al-Assad has been in power since 2000.

This regime appeared stable, but when Arab Spring protests began in 2011, it turned out not to be. Syrians were clearly sick of the country's corruption, brutality, and inequity. Protests began that spring. Though the protests weren't about sectarian issues, many of the protesters were from the country's largest demographic group, the long-disadvantaged Sunni Arabs.

On March 18, Syrian regime forces opened fire on peaceful protestors in the southern city of Deraa, killing three. Protests grew, as did the increasingly violent crackdowns. Assad's troops shot demonstrators en masse, abducted and tortured activists, and even murdered children.

Perhaps inevitably, Syrians took up arms to defend themselves. Defectors from Assad's regime joined them. By early 2012, the protests had become a civil war. Government forces indiscriminately bombed and shelled civilian populations; Assad aimed to crush the rebels and their supporters by brute force.

Assad deliberately targeted Syria's Sunni Muslim majority, civilian and rebel alike. His goal was to polarize the conflict on religious lines, to turn what began as a broad-based uprising against a dictator into a sectarian war, with religious minorities on his side. He knew this would attract extremists to the rebel side, which would make the world afraid of seeing Assad lose.

It worked. By 2013, hard-line Sunni Islamists had become some of the most effective anti-Assad fighters, backed by Sunni states like Saudi Arabia and Qatar. Iran's Shia government backed Assad with cash, weapons, and soldiers. The conflict became, in part, a Middle East sectarian proxy war of Shia versus Sunni.

Meanwhile, a Sunni extremist group known as al-Qaeda in Iraq, which had been mostly defeated in 2007, was rebuilding itself. It grew strong fighting against Assad in Syria, and later swept northern Iraq under the new name ISIS.

By 2014, Syria was divided between government, rebel, ISIS, and Kurdish forces. (The Kurds, an ethnic minority, have long sought independence.) It is divided in a terrible stalemate, as this animated map of the conflict's front lines since March 2014 shows:

Civilians always suffer most in war, but Syria's have suffered especially. Assad targets them ruthlessly, including with barrel bombs and chemical weapons. ISIS and other groups, when they take over towns, put them under brutal and violent rule. Fighting has flattened entire neighborhoods and towns.

Most of Syria's 4 million refugees have ended up in overcrowded and underfunded camps in neighboring countries. But with little hope of returning home, many are seeking new lives in Europe, though the journey is expensive, uncertain, and often fatal. That they would risk so much speaks to the horrors they're fleeing, and to their hopes, however faint, of finding a future for their children.

4) Why is the journey so dangerous?

There are two culprits: the exploitative criminal networks that move the refugees for high fees but offer them little safety, and the Western governments that have tolerated these dangers, at times as part of a deliberate effort to discourage refugees from attempting the journey.

Last fall, for instance, the UK cut funding for the Mare Nostrum search-and-rescue operations that saved an estimated 150,000 people in one year, saying the rescues encouraged more people to make the crossing. The Italian government ended the operation in November. Since then, it has been replaced by the EU's far more limited Frontex program, which only patrols within 30 miles of the border and does not have a search-and-rescue mission.

The result, predictably, has been deadly: An estimated 2,500 people have already died so far this summer. This is not an accident. It is the result of European policy meant to keep out refugees. But, again, this isn't just a European phenomenon — the pattern looks pretty similar in other rich countries, as well.

Australia, for example, has gone to great lengths to prevent so-called "boat people" from reaching its shores, including imprisoning them in abusive detention centers on remote Pacific islands, and shipping them off to Cambodia.

In North America, the US has stepped up enforcement efforts after last year’s child migrant crisis, including sending aid to Central American countries in exchange for efforts to keep children from making the journey to the United States. As with Europe and other countries, the whole idea is to keep refugees from showing up in the first place — even though these efforts never solve, and often don't even address, the underlying crises that cause the refugees to flee in the first place.

5) Why are Western countries making it so difficult for refugees to come?

Some of this is about issues that are particular to the US and to Europe and Australia, but there is also a generalized anti-immigration sentiment playing out across the developed countries where refugees are arriving.

Europe, like a lot of places, has pretty robust anti-immigration politics. The British tabloid press, for example, has for years scaremongered about the supposed threats from refugees and migrants. Such politics, in Europe or elsewhere, often get described as being about pure racism or xenophobia, but in fact they're about something a little different: a fear, rarely articulated, of changing demographics and civic identity.

Taking in large numbers of refugees requires accepting that those refugees might bring changes to your nation's identity or culture. And while that change is often economically and culturally enriching, it can still feel scary. It requires people to modify, ever so slightly, their vision of what their town and neighborhood look like. That change can be hard to accept. You can see this play out in Europe, for example, in the regular political backlashes against new mosques being constructed. Those backlashes are partly about Islamophobia, but they are also an expression of people's fear and insecurity about "losing" what made their community feel familiar.

And anti-immigration sentiment tends to rise when people feel economically insecure, as many do in Western countries now. This insecurity can bring a sense of zero-sum competition, even though in fact migration is typically economically beneficial. There is thus enormous political demand within Western countries for keeping out migrants and refugees.

6) Why is Europe so unwelcoming to the refugees?

Refugees are showing up just as the European Union is in the middle of a pretty fraught debate over migration, which is part of the EU's growing political tension over the feasibility of the Union itself.

In the 1990s, the EU introduced something called that Schengen Area that allows near-unlimited migration between EU countries. It's worked well, but not everyone is comfortable with the influx, and the backlash has contributed to right-wing, anti-EU parties in Europe. This gets expressed as generalized hostility against migrants. If you're a politician in, say, France, then you can't call for kicking out the Poles — that would violate EU rules — but you can call for keeping out Nigerian refugees.

European countries are also taking advantage of EU rules to keep refugees out. In theory, the EU's open internal borders mean that it ought to handle refugees collectively. But in practice, most EU member states don't want to take their fair share, and EU rules mean they don't technically have to. Part of how this happens is a European Union rule called the Dublin Regulation, which requires refugees to stay in the first European country they arrive in until their asylum claims are processed. This rule has allowed Europe to push most of the burden onto Greece and Italy, which are overwhelmed with thousands of refugees.

At the same time, countries such as Hungary and Austria are tightening their borders with other European countries to keep refugees from crossing their territory, even en route to other countries like Germany. In Hungary's case, this is apparently intended to discourage refugees from entering the EU at all — Hungarian Prime Minister Victor Orban is openly hostile to refugees, who he believes are a threat to Europe's "Christian character." While Germany has dramatically relaxed its asylum rules, which is a very important step for dealing with the crisis and helping refugees, the rest of Europe has not really followed, and is tightening restrictions rather than loosening them.

Until the EU can take on the refugee crisis collectively, as it's supposed to, the problem will remain unsolved. But the EU may be incapable of coming together on this until it is able to deal with its underlying issues over the Union and whether individual states are really willing to give up a little bit of their separateness to function better together.

7) Why isn't America taking more Syrian refugees?

The US is usually pretty good about resettling refugees — it resettles about 70,000 a year — but has so far badly lagged in resettling Syrians. Since 2011, the UN refugee agency has referred 17,000 Syrians to the US for resettlement, but the US has only resettled about 9 percent of those.

The US process for applying for resettlement can take up to 24 months for Syrians, due in part to extensive background checks and enormous paperwork requirements. The US can get away with imposing a long, painstaking bureaucratic process because it is voluntarily resettling Syrian refugees who are an ocean away. By contrast, countries that are confronting large groups of refugees who arrive in their territory and request asylum, as Europe is now, do not have that luxury. They cannot legally deport refugees with valid asylum claims, and so in most cases they have to let them stay until their cases have been decided.

But America's bureaucratic resettlement process, like its low acceptance rate for Syrian refugees, comes down in many ways to a fear of terrorism.

"The Obama administration has provided virtually no assurances that the admission of Syrian refugees will not pose a national security threat to the United States," Rep. Michael McCaul, who chairs the Homeland Security Committee, told the New Republic. "If anything, in speaking with leaders in executive branch departments and agencies, I have grown more concerned that we do not have the ability to confidently vet the Syrian refugee population for potential threat actors."

The joke is that the US won't give your family asylum if you once sold falafel to a jihadist, but the darkly humorous punchline is that it's not really a joke at all: The tolerance for "affiliation" with extremists is basically zero, even though it's just about impossible to survive in Syria today without interacting with extremists in some way.

McCaul and some other Republicans have warned that ISIS could exploit any Syrian refugee resettlement program to use as a "a federally funded jihadi pipeline."

The Obama administration knows this isn't true — these are families stuck in camps we're talking about — but it is unwilling to overcome the political opposition. And as with the White House's failure to close Guantanamo, a big factor here is probably a fear of being blamed for a terrorist attack if one were to eventually occur. If the US were to admit, say, 65,000 Syrian refugees, as some humanitarian organizations have called for it to do, and just one of them were to be involved in some sort of attack, then it seems likely the Obama administration would face a severe political backlash.

So while many Americans today say they want the US to resettle Syrian refugees, they have also sent a very clear message that they fear terrorism above almost all else. US leaders have good reason to believe that if even one resettled Syrian committed extremism-tinged violence, they would pay a heavy political cost. The Obama administration appears, at the moment, more concerned with protecting itself against this perceived political risk that with saving the lives of thousands of Syrian families.

8) What's the difference between refugees and migrants?

Not everyone who is crossing the Mediterranean or otherwise showing up at a European or American border is a refugee; many are migrants coming for other reasons. That gets to the distinction between refugees and migrants.

Refugees are people who have been forced out of their home country against their will. The word "migrant" can mean someone who moves to a foreign country voluntarily, or it can be used as a broader umbrella term that includes refugees as well as voluntary migrants. For example, a Syrian man fleeing war is a refugee, whereas a Cameroonian man seeking economic opportunity is a migrant.

Whether someone is considered a refugee or a migrant effects what sorts of legal rights they have: Refugees can apply for asylum and are protected by international and domestic law, for example, while economic migrants cannot. There is no such thing as an "illegal asylum-seeker" — refugees can seek asylum in another country without obtaining a visa or resettlement authorization first. Economic migrants, by contrast, are usually required to have a visa or other form of work authorization in order to immigrate legally.

There is also a meaningful symbolic distinction between the words, one that often becomes political. Calling a group of people "refugees" can be a way of describing them as legitimately deserving of shelter and care, whereas calling them "migrants" can be a way of accusing them of arriving for economic reasons, and perhaps even lying about their asylum claims. This is why anti-immigration politicians will sometimes insist that a group of refugees are actually migrants who have come to exploit Western entitlement programs. And it is why, in this article and many others on Vox, you will see us use the word refugee rather than migrant when we are referring to people fleeing persecution.

But this distinction, for all its legal salience, is actually quite blurry — and it can also imply, wrongly, that non-refugee migrants should be rejected, that only refugees deserve their rights. Jørgen Carling, a scholar at the Peace Research Institute Oslo, put this well:

The ‘two kinds of people’ argument is further undermined by the drawn-out trajectories of many current migrants. A Nigerian arriving in Italy might have left Nigeria for reasons other than a fear of persecution, but ended up fleeing extreme danger in Libya. Conversely, a Syrian might have crossed into Jordan and found safety from the war, but been prompted by the bleak prospects of indeterminate camp life to make the onward journey to Europe. Regardless of the legal status that each one obtains in Europe, they are both migrants who have made difficult decisions, who deserve our compassion, and whose rights need to be ensured.

Drew Hinshaw, a West Africa–based reporter for the Wall Street Journal, elaborated on Twitter. "In many places I cover, asymmetrical war makes it hard to tell where war/poverty end/begin," he wrote, citing as an example parts of Nigeria where low-level violence and bleak economic opportunities, combined, lead families to decide to try for a better life in Europe.

In such cases, of which there are a great many, the distinction between migrants and refugees — and the implied value of judgment of who does and does not "deserve" to seek a better life abroad — falls apart.

9) I want to help. What can I do?

There are a number of ways refugees are suffering, and thus a number of ways to help alleviate those specific traumas and injustices.

The United Nations refugee agency, UNHCR, is a few billion dollars short on funding just to administer aid to the millions of displaced Syrians. There are a number of excellent charities operating in conflict zones such as Syria and Afghanistan, as well as good governance organizations working to improve political conditions in countries where persecution and corruption contribute to refugee outflows.

There are also charities that help care for resettled refugees, or that provide them with legal council to seek asylum once they arrive in Europe or the US or elsewhere. These are all worthwhile causes that can help translate your time and money into ameliorating refugees' plight.

Ultimately, though, checkbook humanitarianism is not going to solve things. This crisis is about 19 million people who have been forced from their countries and need a new country to call home. Solving it will require resettling them, which will require the countries that can afford to absorb them to overcome their own political anxieties about large-scale immigration.

For those of us who live in those countries, that means accepting that our communities will look and feel different from how they have in the past. It requires adjusting, at least slightly, our vision of what our communities look like, and widening the definition of our culture to accommodate new arrivals, even if their customs and values might seem alien to us. That's not something that has ever come easily to people, but it is the only real solution there is.