“We don’t want them here,” President Donald Trump said on January 27, just before he signed his controversial executive order on immigrants and refugees. “We want to make sure we are not admitting into our country the very threats our soldiers are fighting overseas.”

Thus launched the refugee ban that would be among the first controversies of the Trump administration. As written, that first executive order banned immigrants and visa holders from seven Muslim-majority countries — Iran, Iraq, Syria, Yemen, Libya, Sudan, and Somalia — from entering the US for 90 days. It also was a stop sign for all refugee admissions to the United States for 120 days, barred Syrian refugees indefinitely, and prioritized Christian refugees and other religious minorities.

Federal judges ultimately denied Trump’s mission to halt the program, but the US acceptance rate of refugees nevertheless dipped precipitously for many months. On May 26th that the US State Department unceremoniously restored refugee quotas to near their Obama era levels.

The affect of the ban had already reached refugees fleeing Middle Eastern conflicts in Syria, Iraq, and Yemen, of course, but also refugees from countries far removed from the Middle East — places like the Democratic Republic of Congo, Somalia, Honduras, El Salvador, and Myanmar.

On World Refugee Day it’s worth looking again at the crisis that seems to only grow each year.

More than 65 million people are displaced around the world, the highest number since the Second World War. Some of these conflicts have received more media attention than others, but the plight of each refugee is stark. In Uganda, for example, the number of refuges has swelled in the past year from 500,000 to 1.25 million, according to the United Nations. 86 percent of those refugees are women and children.

It’s important to understand exactly what’s at stake here, and why the United States doesn’t have the luxury of backing away from the problem. Here, then, are some basic answers to the most basic questions about the refugee crisis. They should help you get a much better sense of what’s going on, and what this all means.

1) What is a refugee?

The United Nations defines a refugee as “someone who has been forced to flee his or her country because of persecution, war, or violence.” It continues:

A refugee has a well-founded fear of persecution for reasons of race, religion, nationality, political opinion or membership in a particular social group. Most likely, they cannot return home or are afraid to do so. War and ethnic, tribal and religious violence are leading causes of refugees fleeing their countries.

The 1951 Refugee Convention (part of the broader Geneva Convention) was created in direct response to the Holocaust and the failure of the Allies to save 6 million Jews.

The convention set the international definition of who is a refugee — and those who would not be considered refugees (war criminals, namely) — what rights refugees have, and what legal protections and other assistance they should be given by the countries that signed the document.

The “core principle” of the agreement stated that refugees should not be returned to nations where they face “serious threats to their life or freedom.” Originally limited to refugees from Europe, it was modified in 1967 to encompass a wider geographic scope and a broader set of people.

According to the UN’s refugee organization, the UN High Commissioner for Refugees (UNHCR), refugees eligible for resettlement fall broadly into a few categories: women and girls at risk, survivors of violence and/or torture, family reunification, medical needs, children and adolescents at risk, and those who lack “foreseeable alternative durable solutions.”

Migrants, by contrast, often choose to leave their home countries for a wide range of reasons that can range in complexity, from hopes for better education to economics. Those reasons may themselves be arduous, but economic migrants are not considered nearly as vulnerable or at risk as the other groups, and, importantly, they still enjoy the protections of their home governments. For the majority of refugees, unlike migrants, returning home is not an option.

The image many Americans have of a refugee is either very modern — the devastating image of tiny Aylan Kurdi, the 3-year-old Syrian boy who drowned in the Mediterranean while fleeing his war-torn homeland and washed up on a Turkish shore — or historical: Jewish refugees aboard a crowded ship, fleeing Nazi terror, and a single, iconic child who was denied entry to the US and perished because of it: Anne Frank.

That those two children bracket our concept of a refugee is no surprise.

The world’s response, or lack thereof, to the attempted annihilation of the Jews in Nazi-occupied Europe has largely informed our idea of Europe and America as a safe haven in the decades since the war. That explains why, when we speak of refugees, we often think of Jews fleeing the Holocaust, or murdered in it.

Since then, millions of people have sought passage to Europe from sub-Saharan Africa and the Middle East. About a decade ago, that pace began to increase, challenging the idea Europe had created of itself, postwar, as a “safe haven.” Europe began to worry about how to absorb the ever-increasing flow of Southern Hemisphere neighbors seeking to move north, how absorption and integration could continue, and if it was working at all.

Then in the summer of 2015, the flow of migrants dramatically increased (more on why a bit later). In the span of just weeks, there was a sudden surge of refugees clamoring for entry into Europe. They traveled packed together in dangerous, unsuitable boats across the Mediterranean, and hiked overland routes that quickly grew clogged with men, women, and children. By the end of that year, more than 1 million refugees had passed through Europe’s borders.

Since then, the enormity of that refugee crisis has dominated headlines and upended the political conversation in Western Europe. While the pace has slowed, it has not stopped, and the big questions about how to absorb so many people in such a short time and how to stop the flow of migrants have not been answered.

2) Okay, but how many people are we talking about?

The UN estimates some 65.3 million people were displaced in 2015. Of that number, 21.3 million were refugees living outside their country of origin, and some 40.8 million were internally displaced — that means they have remained in their country of origin, but have been forced to flee their homes for another region. Fifty-one percent of refugees are children. Just 1 percent of all refugees will ever be resettled. One in every 113 people in the world is a refugee.

These numbers can be hard to wrap your head around in the abstract, so here are some graphs and charts to help you make sense of the sheer scale of the crisis, and how rapidly the refugee population has grown:

3) How many refugees has the US taken in so far?

The Obama administration set a target of 110,000 refugee admissions for fiscal year 2017. According to the Pew Research Center, which used data from the State Department’s Refugee Processing Center, the US had already taken in 26,000 of that number when Trump signed his ban.

With his executive order in January, Trump attempted to slashed the 2017 number of refugees the United States would accept down to 50,000 -- total. It’s a number that few in the resettlement world felt was remotely sufficient. Federal judges ultimately quashed Trump’s efforts to halt the refugee program, but the numbers were depressed by the upheaval and uncertainty for the first months of the Administration. In May the State Department quietly increased quotas on refugees.

To give a sense of scale, in 2016, the US took in 85,000 refugees total. The Obama administration raised that ceiling to respond to the dramatic uptick in displaced people fleeing conflicts around the globe.

In 2016 alone, the Obama administration resettled 12,587 Syrian refugees. The largest numbers of refugees resettled in the US came from the Democratic Republic of the Congo, Iraq, Somalia, and Syria. More than 50 percent of those refugees were settled across just 10 states: California, Texas, New York, Michigan, Ohio, Arizona, North Carolina, Washington, Pennsylvania, and Illinois.

But while politicians have spent a great deal of airtime talking about refugees, the truth is that the United States, mostly because of its geographic remove from conflict zones and border crossings, has not experienced anything close to the pressures of resettlement our European allies have. In 2015, for example, Germany received the largest number of asylum applications — some 441,900.

And even the German absorption of refugees looks thin in comparison with the number that countries in the Middle East have received. Turkey, Lebanon, and Jordan have absorbed the vast majority of Syrian refugees fleeing that conflict.

Lebanon has more than 1 million Syrian refugees now living within its borders; more than 600,000 Syrian refugees are in Jordan (and many more Syrian nationals who are not technically considered refugees), and there are more than 2.5 million Syrian refugees in Turkey. Those numbers have strained the resources of these countries in every area, from medical services to education.

4) What is the vetting process for refugees coming to the US?

Refugees are subjected to the highest level of screening of any traveler coming to the United States. The vetting of a refugee for resettlement to the United States requires a series of interviews and security checks that can often take up to two years.

The vetting process for each individual refugee involves:

Eight government agencies — including the National Counterterrorism Center, FBI, Department of Homeland Security, and State Department

Six security databases

Five separate background checks

Four biometric security checks — that means fingerprints, checked against databases

Three separate, in-person interviews

Two interagency security checks running data against criminal, intelligence, and terrorism databases

The process starts with a series of interviews with the UNHCR, whose officials determine if the person is, in fact, a “refugee” under the UNHCR definition. If the person crosses that threshold, the UN then chooses which resettlement country a refugee will be assessed for entry for; the refugee does not choose. That might be determined by family members already in a particular country, or other factors that would determine where a refugee might best integrate.

Only 1 percent of all refugees are recommended for resettlement globally. If the UN recommends a refugee for resettlement in the United States, the process continues with a series of interviews and security checks. It involves a first-round interview with a government-funded “Resettlement Support Center” (RSC) — basically a government contractor, such as the International Organization for Migration (IOM), Church World Services, and HIAS. The RSC collects data — documents, materials for biometric tests — and starts a file.

Then the refugee has screening interviews with a series of US government agencies, including the National Counterterrorism Center, the FBI, the Department of Homeland Security, and the State Department.

Refugees from Syria have an additional layer of screening, involving additional interviews with US intelligence agencies and the State Department. As Mostafa Hassoun, a Syrian refugee, described to Politico this week, every step of the way, a security officer checks to make sure the story told by the refugee matches the story he told the last officer.

At each point, a refugee must prove her case. At each point a refugee can be flagged and pulled out of the system, which brings an end to the application process. If any piece of information changes, the entire process starts all over again.

After all of those screenings, which normally take 18 months to two years in total, the UNHCR works with one of nine preapproved nongovernmental organizations, six of which are faith-based, to find jobs, a community to settle the refugee in, and other assistance — including cultural orientation and language training— to help the refugee better integrate into American culture.

5) What are they fleeing from?

The question is broad and specific to each country. But for the most part, refugees are “fleeing active war zones, bombings, street fighting,” says Jason Cone, executive director of Doctors Without Borders, which works in nearly 70 countries on medical and humanitarian responses to those displaced from their homes.

The massive surge in the number of refugees in 2015 was partly a result of the Arab Spring and its aftermath. The Arab Spring was a series of popular, pro-democracy uprisings in the Middle East and North Africa that began in early 2011 and eventually plunged a number of previously stable countries in the region into total chaos. Two in particular, Syria and Libya, played critical roles in creating the refugee crisis.

In Syria, President Bashar al-Assad responded to the largely peaceful uprisings with brutal violence, launching a bloody civil war that has killed over 470,000 people and displaced over 11 million since it began in 2011.

Libya’s longtime dictator Muammar Qaddafi was finally toppled in October 2011 (he first seized power in 1969) with help from the US and NATO. The political vacuum left in his wake gave rise to dozens of rival armed factions vying for power. Since Qaddafi’s death, more than 5,000 people have been killed, and Libya, which had for decades served as a sort of buffer keeping migrants and refugees away from European waters and shores, became one of the main transit points for refugees fleeing the Middle East and Africa for Europe.

Yemen, another country on Trump’s original ban list, is in the midst of a two-year-old war between the Houthi rebels and the government of President Abdrabbuh Mansour Hadi, backed by Saudi Arabia and its allies (including the United States). The BBC reported that, as of October 2016, some 6,800 people had been killed and more than 35,000 injured — most in airstrikes by the Saudi-led coalition.

In January, the United Nations announced that Yemen is on the brink of a country-wide famine, with 2.2 million children “acutely malnourished.” The UN estimates that fighting has driven some 3 million people from their homes, but the majority of those (2,205,102) are internally displaced.

Refugees from Somalia — also on Trump’s first list of banned countries — are fleeing what is essentially a failed state. A bloody conflict that has been raging more or less all the way back to the early 1990s, widespread famine, and drought have combined to leave some 1.5 million Somalis as refugees outside their country; nearly 400,000 live in the Dadaab refugee camp in neighboring Kenya. Somalis represented the fourth-largest number of refugees the US had taken in over the past few years, with nearly 9,000 arriving in 2015.

According to the UNHCR, some 3.1 million Iraqis are displaced within their own country. While Iraq was a leading source of refugees in 2013 and 2014, the number of Iraqis seeking asylum and resettlement has dropped significantly in recent years.

A number of Iraqis who served as translators and guides for American troops have tried to come to this country. Many felt they were at risk precisely because they had helped Americans. As reported by Fortune magazine, some 7,000 former translators and interpreters came into this country under a Special Immigrant Visa; several hundred more had applied under the same program, and nearly 60,000 more had applied for entry through a different program when Trump issued his ban.

And, of course, the refugee problem extends far beyond the few countries on Trump’s list. Millions of Afghans have been displaced by the ongoing war there. Central American drug trafficking and sexual violence, particularly in El Salvador, Guatemala, and Honduras, has sent women and children into Mexico and the United States. In Myanmar, a brutal crackdown on the Rohingya Muslims continues to displace families.

6) What is life like for a refugee?

Refugees don’t just experience violence in their home countries; they are also almost “universally victimized while they flee,” Doctors Without Borders’ Cone says — including becoming victims of torture, enslavement, and sexual violence in transit. “They have to leave almost all their material possessions by the time they have reached any kind of international assistance,” he says.

“Most Americans probably presume that being a refugee or displaced is short term,” Cone explains. “The reality is that most people, once they flee, are displaced on average for 17 years.”

Once a refugee arrives at a transit camp, life may become less immediately dangerous, but it does not become much more comfortable, nor is it always safe. Camps in Africa, like the Dadaab camp in Kenya, have long since passed capacity. Refugee camps in Turkey, Jordan, and Lebanon are stretched to the breaking point by the Syrian crisis. The refugee camps there are overcrowded, insufficient, and bursting at the seams.

Due in part to Trump’s refugee ban, those refugees will likely not see relief anytime soon.

7) Why was Trump’s 120 day ban a problem? Couldn’t they just wait?

Many refugees have waited for years, even decades, to get a chance to come to the United States. Melanie Nezer, vice president for policy and advocacy for HIAS, a global Jewish nonprofit that protects refugees, explains that it’s very rare to make it through all the security clearances and to be accepted — it’s almost like “winning the lottery,” she says.

But, she says, “Because our security clearances are so stringent, the most stringent in the world, all the clearances expire and they are only good for a certain period of time.”

In other words, refugees going through this elaborate process don’t get to continue moving forward once this ban finally expires. Refugees pulled off flights during the original confusion of Trump’s refugee ban likely saw all of their security and medical clearances expire. They then had to start all over again — that means all those interviews, all those assessments. And that could take another two years.

Rev. Scott Arbeiter is president of World Relief, an evangelical Christian organization that works with the US government to resettle refugees in the United States. Last year, it helped resettle 11,000 refugees — about 10 percent of the total number accepted by the United States — from Congo, Myanmar, Syria, Iraq, Afghanistan, and elsewhere.

When we spoke in January he told me there was “no question that this policy further traumatizes some of the most vulnerable people that this world has known,” Arbeiter said. “It continues to keep families separated. Seventy percent of the families we resettle are family reunifications. And 70 percent of the refugees are women and children.”

“We have slammed the door in their face,” he added.

8) Trump says refugees are dangerous. Are they?

The short answer is no.

Immigrants in general, and refugees in particular, are among the least statistically likely people in American society to commit crimes of any kind. Over at the Cato institute, a libertarian think tank, Alex Nowrasteh has been crunching the numbers on refugees for the past few years. In 2015, he wrote, “Of the 859,629 refugees admitted from 2001 onwards, only three have been convicted of planning terrorist attacks on targets outside of the United States, and none was successfully carried out.”

“The terrorist threat from Syrian refugees in the United States is hyperbolically over-exaggerated,” wrote Nowrasteh, “and we have very little to fear from them because the refugee vetting system is so thorough.”

What’s more, as Vox’s Jennifer Williams notes, none of the perpetrators of the major US terrorist attacks carried out in the name of Islam in the past 15 years have come from the seven nations on Trump’s banned list.

Nor is it the case that American Muslims, immigrant or no, pose an outsize threat to their fellow Americans. Vox’s Zack Beauchamp reported last week that terrorism by Muslims makes up just one-third of 1 percent of all murders in the US.

“[T]he bottom line is that adopting extremist views and committing horrendous acts of violence in the name of some ‘righteous’ cause, be it religion or politics or just plain old hatred, isn't something that only Muslims, or Arabs, or immigrants do,” Williams writes.

“[B]etween 2001 and 2015, more Americans were killed by homegrown right-wing extremists than by Islamist terrorists,” she explains. “Banning people from a few Muslim-majority nations won’t reduce the terror threat. And it definitely won’t eliminate it.”

9) Trump’s ban originally privileged Christian refugees -- why was that controversial?

The original executive order included a provision stating that Christian refugees and other religious minorities will be prioritized.

In an interview with the Christian Broadcasting Network on January 27th — the same day Trump signed the executive order — Trump said that Christians in Syria were “horribly treated” and claimed that under previous administrations, “if you were a Muslim you could come in, but if you were a Christian, it was almost impossible.”

This was a distortion. While slightly more Muslims were admitted into the United States than Christians in 2016, the numbers were nearly identical. The New York Times recently reported that “in 2016, the United States admitted almost as many Christian refugees (37,521) as Muslim refugees (38,901), according to the Pew Research Center.”

To be sure: Christians in Iraq and Syria, especially in areas controlled by ISIS, are often targeted for violence and slaughter, and have faced horrific upheaval. But the same is true for Muslims.

Many Christian leaders in the US were deeply unhappy with Trump’s plan to prioritize Christian refugees over Muslims.

“We would reject any policy that placed the suffering of one group of human beings over another,” Arbeiter told me the week the ban was signed. “Muslims are suffering in equally horrendous ways. We are eager to welcome persecuted Christians, but we reject the notion we should have a religious test. When you are vulnerable, when you are fleeing terror, we shouldn't be asking what religion you are.”

Furthermore, denying religious groups the opportunity to serve the refugees is contrary to their faith. Arbeiter pointed to the number of times the word stranger is used in the Bible.

“We are responsible to the widow, the orphan, and the stranger,” he said, “and if we fail to attend to that population, we have lost a part of our identity which is essential to who we are as people of faith.”