The world is grappling with its biggest migrant crisis since World War Two. To understand, it’s important to distinguish between refugees and migrants.

Refugees on a beach in Kos, Greece, 12 August 2015 (AP Photo/Yorgos Karahalis)

See also our Decoder on migration crises.

If it were a country, the “nation of the displaced” would be the 24th largest in the world.

The numbers of people around the world who have been uprooted from their homes have reached levels not seen since World War Two. Waves of desperate migrants crossing Europe and featured prominently in news reports are part of a larger global crisis.

But to understand the issue, it is important to know that migration takes various forms. The difference between refugees and migrants is crucial.

Migrants or refugees?

People leave their countries for different reasons.

• Migrants move voluntarily from one place to another. Economic migrants move to improve their quality of life and generally head to a developed country.
• Refugees flee for security reasons — war, persecution, human rights abuses. The 1951 UN Refugee Convention gives refugees the right not to be immediately deported.
• Other categories are internally displaced, people who have fled their homes but remain within their country, and asylum seekers.

Forced displacement

The UN High Commissioner for Refugees (UNHCR) counts 59.5 million people forcibly displaced worldwide — roughly the population of Italy:

• 38.2 million internally displaced
• 19.5 million refugees
• 1.8 million asylum seekers

To give an idea of the crisis:

• 42,500 people per day were forced to leave their homes last year — a four-fold increase in four years, according to the UNHCR.
• 8.3 million more people were forcibly displaced last year — the biggest yearly increase ever.
• The number of refugees under UNHCR mandate grew by 23% in 2014, bringing the total to the highest level in two decades.

Economic migrants

But not all of the people risking their lives in rickety boats or on overland passage are forcibly displaced.

Economic migrants total more than 230 million, according to the Organisation for Economic Co-operation and Development.

More numerous than refugees, migrants move for different reasons such as work and study. Western countries are the main destinations: the United States for Mexicans and other Latin Americans, northern Europe for many Africans.

Where do they come from?

Many of the men, women and children seeking refuge in Europe are part of a growing tide fleeing conflict in the Middle East or Africa.

More than half of the refugees come from three countries:

• Syria has been torn by civil war since 2011. The UNHCR estimates the number of Syrian refugees worldwide tops 4 million, with 7.6 million displaced inside of Syria.
• War and insurgency have engulfed Afghanistan for almost four decades. There are an estimated 2.59 million Afghan refugees.
• A civil war in Somalia has killed 500,000 people since 1991. There are 1.11 million Somali refugees.

Conflicts in South Sudan, Eritrea, the Democratic Republic of the Congo and Ukraine have each caused massive displacements.

An age-old problem

Refugees are not a new phenomenon. From Huguenots expelled from 18th century France to Jews fleeing the Holocaust during World War Two, refugees are etched in history.

Source: UNHCR

• During the 1948 Arab-Israeli war, most Palestinian Arabs lost their homes. More than 5 million Palestinian refugees live in neighboring countries under UN mandate today.
• During the Bosnian war of 1992-95, half of the Bosnian population was displaced. Today, 620,000 are refugees or internally displaced.
• In 1994, following the genocide of 500,000 Tutsis by Hutus, 2 million people fled Rwanda.
• War in Darfur, Sudan in 2003 provoked the displacement of 2.5 million.
• The Iraq war that started in 2003 uprooted 4.7 million Iraqis from their homes.
• In Colombia, 4 million people have fled a civil conflict since the 1960s, according to the UN.

Where do refugees go?

In 2014, the country hosting the most refugees was Turkey (1.59 million), followed by Pakistan, Lebanon, Iran, Ethiopia and Jordan.

The top 10 countries account for 57% of all refugees. No Western country figures among the top 10, although Germany, which could take in more than 800,000 migrants this year, might be on it by year’s end. The surge in refugees fleeing to Europe stems in part from overcrowding in camps in countries neighboring Syria.

One major issue facing European governments is how to distinguish between refugees and economic migrants. And to determine how willing their citizens are to welcome the displaced.