International migrant stocks

International migrant stocks are estimates of "the total number of international migrants present in a given country at a particular point in time" (UN SD, 2017: 9). United Nations (UN) data on these stocks are based mostly on the country’s population that is born abroad, and (where this information is not available) on holding a foreign citizenship (UN DESA, 2016: 4; UN SD, 2017). 

Data on migrant stocks are often reported together with data on migrant flows. Although both terms account for the number of migrants, what they measure is different. Migrant flows data account for the number of migrants entering or leaving during a specified time period (usually one calendar year) (UN SD, 2017).