Movement of people, most often through migration, is a significant part of global integration. Migrants contribute to the economies of both their host country and their country of origin. Yet reliable statistics on migration are difficult to collect and are often incomplete, making international comparisons a challenge.

In most developed countries, refugees are admitted for resettlement and are routinely included in population counts by censuses or population registers. Globally, the number of refugees at end 2010 was 10.55 million, including 597,300 people considered by UNHCR to be in a refugee-like situation; developing countries hosted 8.5 million refugees, or 80 percent of the global refugee population.

Global migration patterns have become increasingly complex in modern times, involving not just refugees, but also millions of economic migrants. But refugees and migrants, even if they often travel in the same way, are fundamentally different, and for that reason are treated very differently under modern international law. Migrants, especially economic migrants, choose to move in order to improve the future prospects of themselves and their families. Refugees have to move if they are to save their lives or preserve their freedom. They have no protection from their own state - indeed it is often their own government that is threatening to persecute them. If other countries do not let them in, and do not help them once they are in, then they may be condemning them to death - or to an intolerable life in the shadows, without sustenance and without rights.
Refugee population by country or territory of asylum
There are difficulties in collecting accurate statistics on refugees. Many refugees may not be aware of the need to register or may choose not to do so, and administrative records tend to overestimate the number of refugees because it is easier to register than to de-register. In addition, most industrialized countries lack a refugee register and are thus not in a position to provide accurate information on the number of refugees residing in their country. Many countries have registries that are only maintained at the local level, so the data is not centralized.

Asylum-seekers are persons who have applied for asylum or refugee status, but who have not yet received a final decision on their application. A distinction should be made between the number of asylum-seekers who have submitted an individual request during a certain period ("asylum applications submitted") and the number of asylum-seekers whose individual asylum request has not yet been decided at a certain date ("backlog of undecided or pending cases"). Caution should therefore be exercised when interpreting data on asylum-seekers.

The United Nations High Commissioner for Refugees (UNHCR) collects and maintains data on refugees, except for Palestinian refugees residing in areas under the mandate of the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA). Registration is voluntary, and estimates by the UNRWA are not an accurate count of the Palestinian refugee population. The data shows estimates of refugees collected by the UNHCR, complemented by estimates of Palestinian refugees under the UNRWA mandate. Thus, the aggregates differ from those published by the UNHCR.

Statistics concerning the former USSR have been reported under the Russian Federation, those concerning the former Czechoslovakia have been reported under the Czech Republic and those concerning the former Yugoslavia and 'Serbia and Montenegro' have been reported under Serbia. Since 2006, separate statistics are available for Serbia and for Montenegro. Prior to 2006, no separate statistics are available and both countries have been reported under Serbia.
Refugees are people who are recognized as refugees under the 1951 Convention Relating to the Status of Refugees or its 1967 Protocol, the 1969 Organization of African Unity Convention Governing the Specific Aspects of Refugee Problems in Africa, people recognized as refugees in accordance with the UNHCR statute, people granted refugee-like humanitarian status, and people provided temporary protection. Asylum seekers--people who have applied for asylum or refugee status and who have not yet received a decision or who are registered as asylum seekers--are excluded. Palestinian refugees are people (and their descendants) whose residence was Palestine between June 1946 and May 1948 and who lost their homes and means of livelihood as a result of the 1948 Arab-Israeli conflict. Country of asylum is the country where an asylum claim was filed and granted.
The United Nations High Commissioner for Refugees (UNHCR) collects and maintains data on refugees in their Statistical Online Population Database. The refugee data does not include Palestinian refugees residing in areas under the mandate of the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA). However, the Palestinian refugees living outside the UNRWA areas of operation do fall under the responsibility of UNHCR and are thus included in the Statistical Online Population Database.

Refugees are an important part of migrant stock. The refugee data refer to people who have crossed an international border to find sanctuary and have been granted refugee or refugee-like status or temporary protection. There are three main providers of refugee data: governmental agencies, UNHCR field offices and NGOs. Registrations, together with other sources - including estimates and surveys - are the main sources of refugee data. In the absence of Government estimates, UNHCR has estimated the refugee population in most industrialized countries, based on recognition of asylum-seekers. Prior to 2007, resettled refugees were included in these estimates.

Up to and including 2006, to ensure that the refugee population in countries that lack a refugee registry is reflected in the global statistics, the number of refugees was estimated by UNHCR based on the arrival of refugees through resettlement programmes and the individual recognition of refugees over a 10-year (Europe and, since 2006, the United States) or 5-year (the United States before 2006, Canada and Oceania) period. Starting with the 2007 data, the cut-off period has been harmonized and now covers a 10-year period for Europe and non-European countries. Resettled refugees, however, are excluded from the refugee estimates in all countries.

The 2007-2011 refugee population category includes people in a refugee-like situation, most of who were previously included in the Others of concern group. This sub-category is descriptive in nature and includes groups of persons who are outside their country or territory of origin and who face protection risks similar to those of refugees, but for whom refugee status has, for practical or other reasons, not been ascertained.

Asylum seekers - people who have applied for asylum or refugee status and who have not yet received a decision or who are registered as asylum seekers - and internally displaced people - who are often confused with refugees - are not included in the data. Unlike refugees, internally displaced people remain under the protection of their own government, even if their reason for fleeing was similar to that of refugees.

Palestinian refugees are people (and their descendants) whose residence was Palestine between June 1946 and May 1948 and who lost their homes and means of livelihood as a result of the 1948 Arab-Israeli conflict.
Refugees are people who are recognized as refugees under the 1951 Convention Relating to the Status of Refugees or its 1967 Protocol, the 1969 Organization of African Unity Convention Governing the Specific Aspects of Refugee Problems in Africa, people recognized as refugees in accordance with the UNHCR statute, people granted refugee-like humanitarian status, and people provided temporary protection. Asylum seekers -- people who have applied for asylum or refugee status and who have not yet received a decision or who are registered as asylum seekers--are excluded. Palestinian refugees are people (and their descendants) whose residence was Palestine between June 1946 and May 1948 and who lost their homes and means of livelihood as a result of the 1948 Arab-Israeli conflict. Country of asylum is the country where an asylum claim was filed and granted.