Understanding immigration patterns is possible by first understanding immigration theory. The theory of the causes of immigration states that patterns of immigration are impacted by different push and pull factors. Push factors are those that serve to motivate individuals to leave the country of origin. While pull factors are usually motives for wishing to enter a certain country. In the case of economic migration – low wages or a financial crisis in the state of origin would be considered push factors, while economic prosperity and higher wages in another country – would play the role of pull factors.

That is how immigration works, people always move to a place that they consider better for them – there is always a reason, even if the reasons can be very different and sometimes quite ambiguous. Immigration is not a simple matter, and in the modern world there is often much in the way of legislation which must be adhered to, in order that immigration will not be considered illegal. Very often barriers are being put by states, in order to limit and control the flow of immigrants. Barriers may be in a form of legal regulations, welfare level requirements, or it may even be of a social, political or religious nature. The aim of states who set such regulations is always the same – to make sure that they get the immigrants that they want, while they keep away those who they do not.

Very often people, who are not able to immigrate legally, and driven by such factors as war, religous persecution, repression or genocide, are forced to immigrate illegally in order to escape threat. Sometimes immigration is for more personal reasons, such as family reunification, relationships. Criminal evasion may also be a reason for immigration, but usually it is considered illegal, especially, if the crime is recognised internationally. For some people an opportunity to obtain a better education is a pull factor, however, usually international students are not classified as immigrants. Retirement migration is also very common. Very often seniors from expensive countries move to cheaper countries with better climates, which is a new type of international migration.

Not all countries are equally interested in immigrants. While some countries find it a good source of cheap labour, others try to attract only wealthy, well qualified immigrants, which can result in the creation of a selective immigration policy. An extreme example would be Australia, which several decades ago executed the White Australia policy. Today this policy has disappeared, but still priority is usually given to educated, skilled and wealthy immigrants.