Europe is in the grip of a border crisis, with hundreds of thousands of men, women and children attempting dangerous journeys to reach the continent.
But what is the correct terminology to describe these people?
There's been some controversy over the way officials and some news organizations have used the terms "refugees" and "migrants" when discussing this mass movement from East to West.
In its reporting, NBC News recognizes the situation involves both "refugees" and "migrants," using the definitions set out under international law.
Here's all you need to know about what these words mean.
The definition of a refugee, under international law, is someone fleeing armed conflict or persecution. Many of those attempting to travel through Turkey and Greece are refugees, having fled violence and oppression across the Middle East.
One of the biggest groups of refugees are Syrians who have fled the country's grinding civil war and ISIS' campaign of violence. Almost 350,000 refugees from the country have applied for asylum in Europe since April 2011.
"Their situation is often so perilous and intolerable that they cross national borders to seek safety in nearby countries," the United Nations' refugee agency UNHCR said in its definition of refugees. Once recognized, these people are protected under international law and can receive humanitarian assistance.
"It is too dangerous for them to return home and they need sanctuary elsewhere," the U.N. body said.
A smaller proportion of those crossing into Europe are from countries where there is no ongoing conflict and where they have not been persecuted. These people are known as migrants, or "economic migrants."
Unlike refugees, these people were not forced to flee, but many of them traveled to Europe seeking a better life. These may involve increased job or education prospects or meeting up with family members living in their intended destination.
Some of the people traveling across the Mediterranean Sea from northern Africa, as well as some of those staying in camps in the French port of Calais, may fall into this category.
"Before they leave their countries, migrants are able to research their destinations, explore employment opportunities, and study the language of the country where they plan to live," according to the International Rescue Committee, a New York-based humanitarian organization.
They key difference is that if migrants chose to return home, they would likely continue to receive the protection of their government — unlike refugees.
Why is the distinction important?
According to the UNHCR, "conflating refugees and migrants can have serious consequences for the lives and safety of refugees."
If Western governments and media organizations give the impression that people fleeing strife are the same as those choosing to move West for a better life, it "takes attention away from the specific legal protections refugees require," the UNHCR said.
"Migrants, especially economic migrants, choose to move in order to improve the future prospects of themselves and their families," whereas "refugees have to move if they are to save their lives or preserve their freedom," it said.