Their homelands are torn by war, economic distress, political strife, or environmental collapse. They choose to leave, or have no choice. They're called migrants, refugees, or internally displaced people. The labels are inadequate as often circumstances could allow all three descriptions, or some combination of them. Once in their new countries, they face difficult transitions, discrimination, or outright hostility. Host countries are burdened with the economic and political repercussions of the arrivals, while home nations are sometimes saddled with a "brain drain" of their most important human resources. Immigration is a hot-button issue in the American presidential race, and a wave of new arrivals from Libya to Italy has left the European Union struggling with decisions over the Schengen policy of borderless travel between member nations. Gathered here are images of some of the estimated 214 million people worldwide in the process of redefining what "home" means to them.
1. Rescuers help people in the sea after a boat carrying some 250 migrants crashed into rocks as they tried to enter the port of Pantelleria, an island off the southern coast of Italy, on April 13. Italy is struggling to cope with a mass influx of immigrants from north Africa, many of whom risk their lives by sailing across the often stormy Meditteranean in makeshift vessels. (Francesco Malavolta/AFP/Getty Images)
2. Immigrants from Latin America and Asia show up inside a truck bound for the US and detected by Mexican police X-ray equipment in Chiapas State, Mexico on May 18. The Police detected more than 500 hundred immigrants inside two trucks at a check point. (AFP/Getty Images)
3. Refugees of the Guere ethnic group sit with their belongings inside a temporary camp set up at a Catholic church in Duekoue, Ivory Coast on May 18. The refugees in this crowded church ground were chased out of their homes by soldiers or ethnic militias during a violent post-poll power struggle between former president Laurent Gbagbo and his rival Alassane Ouattara. Some 27,000 are still too terrified to return home. (Luc Gnago/Reuter)
4. Fire engulfs a building at Sydney's Villawood Detention Centre on April 21. Buildings were set ablaze as asylum seekers also protested on a rooftop within the facility against their failed applications for asylum. (Greg Wood/AFP/Getty Images)
5. Asylum seekers sit on top of a building at Sydney's Villawood Detention Centre during an April 21 protest against their failed applications for asylum. (Greg Wood/AFP/Getty Images)
6. Tunisian would-be immigrants who were evacuated from the Italian island of Lampedusa to a reception center in Manduria, jump over a fence to escape from the camp on April 1. The Italian government has prepared a plan to accommodate 10,000 migrants on a temporary basis, before repatriating them to Tunisia. (Carlo Hermann/AFP/Getty Images)
7. Syrian soldiers prepare to hand over an elderly Syrian woman to Lebanese army troops as she was found trying to cross the border into northern Lebanon on foot on the Syrian side of the border village of Arida on May 19. The family of the woman had already fled their homes for fear of fresh violence as a result of anti-regime protests in their country, leaving her behind. (Joseph Eid/AFP/Getty Images)
8. Afghan asylum seekers, who were caught by a marine police patrol boat off Java while on their way to Australia, walk to a temporary shelter upon arrival at Tanjung Perak port in Surabaya, Indonesia on May 2. Indonesia is a major launching post for Afghans, Iranian and Iraqis seeking refuge in Australia. (Trisnadi/AP)
9. A pregnant woman would-be immigrant arrives at the hospital in Lampedusa on March 26. As a stricken boat carrying some 350 African migrants from Libya neared Italian shores, an Ethiopian woman also gave birth on the boat and was rescued with her newborn baby and the child's father by an Italian navy helicopter. (Alberto Pizzoli/AFP/Getty Images)
10. A police officer instructs Georgina Perez and fellow illegal immigrants to move or face arrest during a protest for rights for higher education for illegal immigrants that blocked traffic in Atlanta. (David Goldman/AP)
11. A boat of Tunisian would-be immigrants arrives in Lampedusa on March 26. A large influx of migrants have arrived on the Italian island from Tunisia since the ouster of president Zine El Abidine Ben Ali in mid-January. (Alberto Pizzoli/AFP/Getty Images)
12. An Italian soldier helps a Tunisian migrant who injured himself trying to escape from the immigrant shelter in Lampedusa, the tiny Italian island close to North Africa where thousands of migrants have arrived in the past weeks on April 11. (Giorgos Moutafis/AP)
13. Ethiopian immigrants fleeing violence in Libya wait at the Lyster Detention Centre in Hal Far, Malta on April 19. (Darrin Zammit Lupi/Reuters)
14. An Ethiopian immigrant holds her two-week old child at the Lyster Detention Centre in Hal Far, Malta April 19. (Darrin Zammit Lupi/Reuters)
15. Julie Ngor serves food as locals enjoy a meal at the Red Rose Restaurant, which specializes in Cambodian, Thai, Chinese and Vietnamese cuisine, at the Palin Plaza in Lowell, Mass. on February 5, 2010. Lowell is working with MIT to explore the possibility of mimicking the successes of ethnic neighborhoods like Boston's North End and Chinatown by "branding" its expansive district of Cambodian immigrants, now the second-largest concentration of Cambodians in the United States. Officials hope it could become a tourist draw and economic engine, while also helping the old mill city update its identity. (Cheryl Senter for the Boston Globe)
16. A Customs and Border Patrol agent patrols along the international border in Nogales, Ariz. (Matt York/AP)
17. More than 1000 mainly African migrants queue at the port in Misrata, Libya waiting to board an International Organisation of Migration ship on May 4 as the city suffered through bombardment. (Christophe Simon/AFP/Getty Images)
18. Some 250 migrants wait in a boat approaching the tiny Italian island of Lampedusa on May 6. (Francesco Malavolta/AP)
19. Youths check a boat on May 10 on a beach in Kram, Tunisia. (Fethi Belaid/AFP/Getty Images)
20. Honduran citizens wait to fill out immigration papers upon arriving at the airport in Tegucigalpa on April 6 after they were deported and flown in by a plane chartered by the U.S. Immigration and Naturalization Service. 45,907 Hondurans were deported after being declared illegal immigrants in the U.S in 2010 and as of the date of this photograph, 9,143 have been deported this year, according to the Honduran Attention Center to Returnee Migrants. (Edgard Garrido/Reuters)
21. Two Greek Roma scavenge for metals among the ruins of an Albanian Roma shantytown at the outskirts of Athens April 9. Greek police say two men have been shot dead and three injured in a fight between scavengers at a rubbish dump on the outskirts of Athens. Police say the victims are believed to be Asian immigrants who clashed with Albanian Roma following a dispute over garbage salvaged from the site for recycling. (Kostas Tsironis/AP)
22. Jewish immigrants from Ethiopia attend a demonstration of a ceremonial seder Passover holiday dinner at an immigrants' center in Mevasseret Zion, Israel April 14. It would be the first "seder" the immigrants would be celebrating in Israel. (Ronen Zvulun/Reuters)
23. Illegal immigrants appear on a night vision monitor screen of the Hungarian border police on the country's southern border with Serbia near Roeszke, Hungary June 25, 2008. British and Hungarian police said on April 19, 2011 they have cracked down on a people smuggling network that brought thousands of Vietnamese into Europe. Ninety-eight smugglers and other members of the network have been arrested since the project began in 2009. (Bela Szandelszky/AP)
24. An alleged illegal immigrant is heavily escorted after attending an habeas corpus hearing at the Justice Palace in Quito on April 19. An Ecuadorean judge analyzed an habeas corpus petition for 21 Sri Lankan and three Pakistani citizens arrested for alleged migratory irregularities. (Rodrigo Buendia/AFP/Getty Images)
25. An Iranian illegal migrant who was detained with dozens of others after their boat landed on a beach on Java island holds his children at an immigration detention center in Cilacap, Indonesia on April 26. Indonesia is a major launching post for Afghans, Iranians, and Iraqis seeking refuge in Australia. (Wagino/AP)
26. A woman shouts during a protest called by immigrants from El Salvador, Guatemala and Honduras against Mexico's immigration law, in front of the Mexican Congress in Mexico City on April 26. (Alfredo Estrella/AFP/Getty Images)
27. Demonstrators march during a May Day protest on May 1 in Los Angeles. Thousands of people marched for immigration reform, among other issues. (Eric Thayer/Getty Images)
28. Julio Cesar, an immigrant from Guatemala, sits on his bunk at the only shelter for immigrants in Mexico City on May 4. A group of 35 immigrants from Central America await in the shelter for the visa promised by Mexican lawmakers. (Omar Torres/AFP/Getty Images)
29. A Romanian border police officer inspects a train car at the border with Moldova. As Romania fights to convince EU partners that it deserves to enter Europe's visa-free zone in 2011, it hopes not to fall victim to growing Schengen skepticism among European states. (Daniel Mihailescu/AFP/Getty Images)
30. People clamber on the rocky shore on Christmas Island, Australia, during a rescue attempt as a boat breaks up in the background December 15, 2010. Australian police charged a man with people smuggling on May 12 in connection with the deadly boat crash that killed 48 asylum seekers. (ABC/AP)
31. A woman stands at the site of a fatal mugging in central Athens May 12. Far-right groups have launched a series of anti-migrant attacks since the mugging, which caused outrage as the victim was apparently killed for his camera as he was about to drive his pregnant wife to a maternity hospital. There is no evidence immigrants were involved in the killing. Police are also investigating the fatal stabbing of a Bangladeshi immigrant in a neighboring area. (Thanassis Stavrakis/AP)
32. A member of the Red Cross holds a child at the southern Spanish port of Motril May 15. Some 65 would-be immigrants, including 25 men, 30 women and 10 children, aboard a fishing boat were intercepted off the southern Spanish coast as they were heading to European soil from Africa. (Jon Nazca/Reuters)
33. A Palestinian refugee plays in front of homes rebuilt by UNRWA, the U.N. agency for Palestinian refugees, which were destroyed in fighting in 2007, in Nahr al-Bared Palestinian refugee camp in northern Lebanon April 19. (Omar Ibrahim/Reuters)
34. Adar Gul, 80, an elderly Afghan refugee, arranges bricks during his daily work at a brick factory on the outskirts of Islamabad May 16. (Muhammed Muheisen/AP)
35. Palestinian demonstrators throw stones toward Israeli border police during clashes in the Shuafat refugee camp on the outskirts of Jerusalem on May 15 as Palestinians marked the "Nakba" or "Catastrophe" of the 1948 creation of Israel. (Ahmad Gharabli/AFP/Getty Images)
36. Israeli border policemen detain a Palestinian protester during clashes in Shuafat refugee camp, in the West Bank near Jerusalem May 15. (Ammar Awad/AP)
37. An internally-displaced Somali woman stands with children outside their makeshift house after floods destroyed their home in southern Mogadishu's Hamarweyne district May 19. (Farah Abdi Warsameh/AP)
38. Tens of thousands of Internally Displaced Persons who fled their village following clashes between the Government of Sudan and rebel movements sought protection at the Zamzam IDP camp in North Darfur March 15. More than 70,000 people have fled fighting in Sudan's western Darfur region in the last three months, swelling numbers at a major refugee camp by more than third, U.N. humanitarian officials said. (Olivier Chassot/Handout/UNAMID)
39. A refugee from Somalia watches through her veil as she protests against the United Nations High Commissioner for Refugees in New Delhi May 16. The refugees demanded either integration with the local community, voluntary repatriation, or resettlement in a third country. (Gurinder Osan/AP)
40. Fieldworker Felix Sanchez takes a drink of water while working on a Vidalia onion farm in Lyons, Ga. Concern is being raised that new legislation, meant to bar illegal immigrants from the workforce, and to give local police increased enforcement powers, will scare away Mexican laborers. (David Goldman/AP)
41. Fieldworkers load a bucket of onions to a waiting truck on a Vidalia onion farm in Lyons, Ga. (David Goldman/AP)
42. Myanmar migrants illegally cross the Thai-Myanmar border on an inner tube, in Mae Sot, Thailand. Refugees who have fled war-torn eastern Myanmar fear for their future after Thailand said it wants to close camps strung out along its border that are home to more than 140,000 people. Among them lives a majority of ethnic Karen who fled their country in the 1990s following a major offensive by the Myanmar government army against the Karen National Union. (Christophe Archambault/AFP/Getty Images)
43. Muslim refugees attend school at the Mae La refugee camp in Thailand near the Thai-Myanmar border. (Christophe Archambault/AFP/Getty Images)
44. An injured Libyan rebel is evacuated aboard an International Organization of Migration ship, which managed to evacuate about 800 people, including stranded migrants and the wounded on May 4 from the port city of Misrata. (Christophe Simon/AFP/Getty Images)
45. Okpara, a 36-year-old immigrant, holds a hand-drawn Israeli flag during a lesson for children of illegal immigrants and foreign workers at a kindergarten in Tel Aviv on May 11. Okpara runs a "pirate" nursery, one of dozens in Tel Aviv offering cut-price daycare to illegal immigrants as figures show that some 100,000 of Israel's 220,000 foreign workers are in the country without permits. (Jack Guez/AFP/Getty Images)
46. Myanmar refugees share a bed in their room in a suburb of Kuala Lumpur, Malaysia. Refugees in Malaysia, mostly from Myanmar, may get the chance to move to Australia following the recent announcement that an agreement would enable 4,000 refugees in Malaysia to move to Australia over a four-year period. (Mark Baker/AP)
47. A Syrian refugee child stands in the new refugee tent compound in Boynuyogun, Turkey, near the Syrian border June 12. Syrian forces launched a crackdown on the Syrian town of Jisr al-Shughour, fueling fears that the clashes could spark a further influx of refugees toward bordering Turkey. (Vadim Ghirda/AP)