Short answers, pulled from the story.
The number of international migrants has reached 244 million worldwide, a 41 percent increase since 2000. The United States hosts the largest share, with 19 percent of the world's total, followed by Germany and Russia, which each host 12 million migrants.
Push factors are conditions that drive people to leave their country of origin, such as poverty, persecution, or natural disasters. Pull factors are conditions that attract migrants to a destination country, such as higher wages, job availability, or family networks.
Research suggests immigration can be beneficial to receiving countries overall, though effects vary. Studies estimate that eliminating migration barriers could increase world GDP by 67 to 147 percent. In Switzerland, winning citizenship increased annual earnings by an average of approximately $5,000 U.S. dollars over 15 years for naturalized immigrants.
A 2018 study in the American Sociological Review found that within racial groups, most immigrants to the United States fully assimilated within 20 years. Immigrants who arrived after 1994 assimilate more rapidly than those who arrived in earlier periods.
A 2016 meta-analysis of 738 correspondence tests across 43 studies conducted in OECD countries between 1990 and 2015 found that equivalent minority candidates need to send around 50 percent more job applications to be invited for an interview than majority candidates. African-American applicants with no criminal record were offered jobs at a rate as low as white applicants who had criminal records.
India has the largest diaspora in the world, with 16 million people living outside their home country. Mexico is second with 12 million, and Russia is third with 11 million.