When it comes to international migration we need to understand the term being used. What it refers to is when a person or persons change their usual place of residence between countries. You will find that the amount of international migrants will usually be a lot smaller than the total amount of persons who are traveling across international frontiers and this is because the majority of those who travel normally don't intend to change their place of residence.
One can contrast international migration with internal migration and this refers to a change of residence that is within a country. Also, the term immigration is used often to point out the flow of people who are establishing a residence in any given country whose last place of residence was in a different country. Then there is the term emigration and this is used to point out the flow of people who are relinquishing their usual place of residence in a country to establish a new place of residence in a different country.
When it comes to a nations population there are four components that they use to calculate the change in their population. Those components are births, deaths, immigration and emigratory events. For most countries though their population change is predominately based upon the balance of births and deaths in their country. There are however, a few countries in certain periods of time that the net international immigration has been a huge component of their total population change.
When it comes to international migration we often see that migration is often the strongest among younger adults who are looking for a new start in life. Often people are influenced to migrate because of persecution, money, resources that are available to help meet their life goals and often because they are simply attracted to a particular country an want to live there as well as better climate, marriage reasons or most serious of all to save one's own life.
Some major streams of international migration over the years have had very important historical consequences. One of the earliest major streams of migration that had a huge historical impact was the westward migration of the nomadic tribes in both Europe and Central Asia, this was during the fall of the Roman Empire. Those who migrated westward during this time include people who spoke Celtic, Germanic and Ural-Altaic languages. As these people move west they pushed out those tribes who were ahead of them. The Central Asian migration was possibly cause from the expanding Chinese Empire that hugely disrupted the life of the nomadic tribes there and provoked them to move to safer areas.
The migration to North America of European and African immigrates began slowly after the voyage of Columbus in 1492. It is estimated that more than 60 million Europeans left their homes in the centuries after Columbus. The migration of Africans was mainly forced migration via slavery. The very first slaves were taken to the Virginia colony in 1619 and this type of slave migration was legal until 1808. During that time slave migration number around 400,00 Africans.
The most current major stream of international migration has been termed as labor migration. This happens when immigrants are legally allowed into a country for certain defined periods of time in order to alleviate any shortage of labor. Those who are labor migrants however, are not allowed.