Migration is of enormous benefit to a country and is not a recent phenomenon. Historical migration of human populations had begun with the movement of Homo erectus out of Africa across Eurasia about a million years ago. Homo sapiens appear to have occupied all of Africa about 150,000 years ago, moved out of Africa 70,000 years ago, and had spread across Australia, Asia and Europe by 40,000 years ago.

While the pace of migration had accelerated since the 18th century already, it has increased further in the 19th century. Manning distinguishes three major types of migration: labour migration, refugee migrations and lastly: urbanization. Millions of agricultural workers left the countryside and moved to the cities causing unprecedented levels of urbanization. This phenomenon began in Britain in the late 18th century and spread around the world and continues to this day in many areas.

Industrialization encouraged migration wherever it appeared. The increasingly global economy globalised the labour market. Atlantic slave trade diminished sharply after 1820, which gave rise to self-bound contract labour migration from Europe and Asia to plantations. Also overpopulation, open agricultural frontiers and rising industrial centres attracted voluntary, encouraged and sometimes coerced migration. Moreover, migration was significantly eased by improved transportation techniques.

Transnational labor migration reached a peak of three million migrants per year in the early twentieth century. Italy, Norway, Ireland and the Quongdong region of China were regions with especially high emigration rates during these years. These large migration flows influenced the process of nation state formation in many ways. Immigration restrictions have been developed, as well as diaspora cultures and myths that reflect the importance of migration to the foundation of certain nations, like the American melting pot. The transnational labor migration fell to a lower level from 1930s to the 1960s and then rebounded.

International migration occurs when persons cross state boundaries and stay in the host state for some minimum length of time. Migration occurs for many reasons. Many people leave their home countries in order to look for economic opportunities in another country. Others migrate to be with family members who have migrated or because of political conditions in their countries. Education is another reason for international migration, as students pursue their studies abroad. While there are several different potential systems for categorizing international migrants, one system organizes them into nine groups: temporary labour migrants; irregular, illegal, or undocumented migrants; highly skilled and business migrants; irregular migrants; refugees; asylum seekers; forced migration; family members; return migrants; and long-term, low-skilled migrants. These migrants can also be divided into two large groups, permanent and temporary. Permanent migrants intend to establish their permanent residence in a new country and possibly obtain that country’s citizenship. Temporary migrants intend only to stay for a limited periods of time; perhaps until the end of a particular program of study or for the duration of their work contract or a certain work season. Both types of migrants have a significant effect on the economies and societies of the chosen destination country and the country of origin.

Similarly, the countries which receive these migrants are often grouped into four categories: traditional settlement countries, European countries which encouraged labour migration after World War II, European countries which receive a significant portion of their immigrant populations from their former colonies, and countries which formerly were points of emigration but have recently emerged as immigrant destinations.

Causes of Migration:

Causes of migrations have modified over hundreds of years. Some cases are constant; some of them do not carry the same importance as years ago. In general we can divide factors causing migrations into two groups of factors: Push and pull factors.

• Push Factors are economic, political, cultural, and environmentally based.
• Pull Factors are economic, political, cultural, and environmentally based.

On the macro level, the causes of migration can be distilled into two main categories: security dimension of migration (natural disasters, conflicts, threats to individual safety, poor political prospects) and economic dimension of migration (poor economic situation, poor situation of national market).

Push and pull factors are those factors which either forcefully push people into migration or attract them. A push factor is forceful, and a factor which relates to the country from which a person migrates. It is generally some problem which results in people wanting to migrate. Different types of push factors can be seen further below. A push factor is a flaw or distress that drives a person away from a certain place. A pull factor is something concerning the country to which a person migrates. It is generally a benefit that attracts people to a certain place. Push and pull factors are usually considered as north and south poles on a magnet. The pull factor plays a significant role in attracting migrants.

Push Factors:

• Not enough jobs
• Few opportunities
• "Primitive" conditions
• Desertification
• Famine/drought
• Political fear/persecution
• Poor medical care
• Loss of wealth
• Natural Disasters
• Death threats
• Slavery
• Pollution
• Poor housing
• Landlords
• Bullying
• Poor chances of finding courtship

Pull Factors:

• Job opportunities
• Better living conditions
• Political and/or religious freedom
• Enjoyment
• Education
• Better medical care
• Security
• Family links
• Industry
• Better chances of finding courtship