1.
Introduction
More than 100,000 years ago the first modern humans left Africa and began to colonize the world. Since then human history is also a history of migration. Migration has always been a strong impetus towards human development, these days however migration is often seen as problem or threat.
Migration is defined as the permanent change of residence of a person or group. It is a natural social phenomenon. Humans have colonized the entire world and penetrated its remotest areas. Migration is taking place within very different contexts: f.e. military conquest, refugees, expulsion or enslavement. But migrants have also traveled in search of economic opportunities, new settlement areas or trade routes. Currently approximately 216,000,000 people are living away from their place of birth. This number equals about 3% of the world population.
Analyzing the reasons for migration one distinguishes between push and pull factors - often both appear together. Push factors are circumstances in the country of origin that lead people to emigrate, for example poverty, war or environmental disasters. Pull factors are conditions in the destination country that make immigration attractive such as economic opportunity and political freedom.

Overall trends
By far the most immigrants live in the United States followed by Russia and Germany. The main countries of origin are Mexico, India, China and Russia.

In proportion to the population Persian Gulf countries host the largest share of migrants - about 35% of their population. They mostly come from South Asia and Egypt. Most migrants in the US come from Latin America, particularly from Mexico. In Europe the origin of immigrants differs considerably between countries and reflects their historical development: in Germany and Denmark a large share of migrants are of Turkish origin, most immigrants in France, Portugal and Spain come from their former colonies. In addition there's a strong migration within Europe. This is promoted by the EU's principle of free movement: citizens of the EU are allowed to live in any EU member-state without any restrictions.

However, if we look at refugees we see that the situation is a little different. They very often find refuge in their neighbour’s countries.

2.
Migrations due to refugees
The UN Convention about the status of refugees, which gave refugees their official status, dates from after the Second World War, in 1951, when millions of people in Europe found themselves stateless. The term ‘refugee’ is usually used to describe people who were persecuted on account of their race, religion, nationality, membership of a particular social group, ethnic group or political conviction in their country of origin. Roughly, it designates people whose freedom or lives are in danger. Because of international conventions, they have a right to be protected by foreign countries. Moreover, nations living at peace and in stable economic conditions are asked to show their solidarity with measures such as the temporary admission of displaced people, peace missions, material and reconstruction aid, etc.

The United Nation Refugee Agency, recently released their latest data dated from january 2011. They were 10,5 millions official refugees in the world and 27,5 millions IDP (internally displaced people). The refugee problem is a global issue because the main countries of origin and destinations are among the poorest in the world. Indeed, since 1980, the country that produces the most refugees is Afghanistan and the continent with the highest number of refugees is Africa. We often assume that refugees try to move to industrialized countries in Europe or North America, but this is far from true. In fact, Pakistan and Iran are the countries receiving the most refugees.
The majority of refugees wait many years for a permanent solution to their exile. The solution for them during that time is to live in a camp, witch is more a political solution than a human one considering that many camps are highly predisposed to violation of rights, like physical or sexual abuse. The UN Refugee Agency considers 3 principals solutions to the exile: return to the country of origins, integration in the country where refugees are living or resettlement in another country. The agency favours the two last solutions as the first one is hardly possible when the conflict is still present. However, contrary to one might think, the return to the country of origins is often chosen by refugees for reasons like family, economy, culture or something else, and that, even if the country haven't change. However, in some case, like in Bosnia, Sri Lanka and Kosovo, the country really puts effort for refugees to come back once the conflict is over.

Even if we often talk about refugees, IDP, which stands for Internally Displaced Peoeple, are a lot more. We count more than 27 millions of them. The two main reasons are the increase of the number of conflicts in countries and the decrease of the willingness of states in assisting people fleeing from their contry. IDPs may also be forbidden to cross borders by the army of the neighbour country or they may prefer to stay near their home waiting for the conflict to end. The problem with IDPs is that their is no official mechanisms for the international community to protect them.

Countries with more than 1 million IDPs : Colombia, Sudan, Democratic republic of Congo, Somalia, Iraq, Turkey

3.
Economical migration

What is economic Migration ?
Economic Migration is when people move to other countries to benefit from their greater economic opportunities. Traditionally this is from least developed countries in the developing south to Developed countries in the affluent north. The main areas for economic migration are: Mexico to the USA; North Africa to Europe; and from territories to their former mother country.
People think about emigrating from places that have few job opportunities. Because of economic restructuring, job prospects often vary from one country to another and within regions of the same country.
People immigrate to places where the jobs seem to be available. An area that has valuable natural resources, such as petroleum or uranium, may attract miners and engineers. A new industry may lure factory workers, technicians, and scientists. Many economic migrants find the reality is very different from their dreams.
Some people experience hostility from their new countrymen and feel they are treated like second class citizens. Many immigrants work on low paid jobs that no one else want to do. Also there is little protection from unscrupulous employers who take advantage of these illegal workers in the terms and conditions they offer. As a result many economic immigrants live in appalling conditions and again find themselves in the poverty trap they sought to leave behind. The overall stock of migrants has not decreased as a result of the economic crisis. In most regions of the world, the total number of migrants in 2010 was higher than in 2005. This is partly due to the fact that immigrants arriving in many countries do not fall under the heading of labour migrants.
However, flows of new migrants have slowed in many parts of the world, reflecting the decline in job opportunities in destination countries, and the impact of restrictive measures made by several countries to reduce labour migration. For example, Singapore, Malaysia and Thailand responded to the economic crisis by ceasing to issue or renew work permits. Recruitment agencies in Egypt and Jordan have reported a drop by up to a half in demand for labour in the Gulf region since the beginning of 2008, especially for skilled labour. The Australian Government reduced the number of permanent and temporary migrants admitted, for the first time in ten years.
The flow of irregular migrants attempting to enter destination countries slowed in 2009–2010. The number of attempted illegal border crossings has fallen by about 1/3 or more in the United States and Europe since 2008. However, border apprehensions are only one measure of irregular migration. Given that many migrant workers have lost their jobs and not returned to their country of origin, it is likely that the number of migrants who are working in precarious forms of employment in the shadow economy has increased.
The global economic crisis has made many migrants around the world more vulnerable, as migrants have been among the first to be affected by job losses. This is reflected in the high unemployment rate for migrants in comparison to natives. For example, the unemployment rate for Mexican and Central American immigrants in the United States (11.4% in June 2009) was greater than the unemployment rate for native-born Americans (9.5%) (MPI, 2009). In Europe, migrant unemployment rates are generally higher than unemployment rates for nationals and grew faster than unemployment rates for nationals between 2008 and 2009.[U1] 4.
Environmental migration
Climate change and its implications for migration have also become a growing policy concern. Most experts agree that migration resulting from environmental change is likely to increase in the foreseeable future, although a significant proportion of this is likely to be internal migration. The most widely cited figure suggests that up to 200 million people could be on the move by 2050, though estimates range from 50 million to 1 billion. What is already certain is that the number of persons displaced by natural disasters is rising as the total number of disasters has increased over the last two decades. In 2008, approximately 20 million people were displaced by climate-related natural disasters (UN-OCHA and IDMC, 2009).
Natural disasters, such as floods and droughts, occur with accelerated frequency today and increasing numbers of people are being affected; one outcome of this is increased migration. The effects of climate change are likely to exacerbate this trend. As migration may be one of several adaptation strategies in the face of natural disasters, distinctions between slow- and sudden-onset events are important.[U2]

5.
Educational migration
Over the last decade student migration has become particularly important, especially in the USA and in some parts of the EU, with generally young adults migrating to take part in university courses and other educational opportunities.
Top two source countries for international students are China and India with 510,314 and 195,107 globally mobile students respectively. The key drivers of mobility of Chinese and Indian students are quite similar: increasing prosperity, which enables the ability to afford foreign education and rapid expansion of the system of higher education at the expense of quality.
According to the United Nations Educational, Scientific and Cultural Organization (UNESCO) there is more than 2.5 million students studying outside their own country. UNESCO also predicted that the number of international students might rise approximately to 7 million by year 2020. The main destinations preferred by international students are the United States, United Kingdom, Germany, France and Australia. Overall, the number of international students more than doubled between 2000 and 2010.
Although student migration may be seen as essentially temporary in nature, significant numbers remain within the destination country after the end of their studies either as labour migrants or following family formation with a person resident in the destination country. Many European countries have specific programmes allowing student migrants to remain in the country to work. For the destination country, such programmes are particularly attractive as they offer the possibility of adding to the national labour force qualified young workers who already have a good level of linguistic and cultural integration. On the other hand the loss of students from sending countries can have a rather detrimental impact on their economy by depleting already scarce resources.

6.
Conclusion

Nowadays migration is often seen as a threat. This is caused by a number of fears: for example the idea that immigrants are expensive and a burden to the welfare system of the destination country. Another fear is that the host country will lose what is perceived as its national identity, especially through the influx of groups from other religions or cultures.

Migrants may not have equal opportunities in obtaining employment and may be subject to discrimination. The cost for housing, educating and unemployment cause resentment within tax paying residents. The government policy of constructing “safe centers” cause racial unrest.
Attitude to Migration depends on economic stability of host country. If in period of recession, migrants are accused of taking jobs. However when in period of economic growth migrants residents do not worry about migrants.

As a result of these fears the migration policies in Western industrial countries, for example the USA, have become increasingly restrictive.

What is not considered most of the time, migration also has positive aspects. It contributes to the economic development at migrants countries of origin. Migrants around the world transfer over $300 billion to their home country each year, that is considerably more than the official development assistance to these countries.
In European countries, as well as in other industrialized nations, such as Japan the birthrate has dropped to a low level below the replacement rate. These countries depend on migration in order to meet its employment needs and to stabilize the retirement system. Finally migration contributes to the cultural diversity of destination countries.

We see that the debate over migration is burdened by fear and prejudice. In order to deal with the problems attached to migration it is especially important to develop and implement a constructive migration policy. Such a policy would include regulated immigration as well as provide right for legitimate asylum-seekers.