In 1972 President Idi Amin expelled Uganda's Asian population from the country. Many emigrated to Britain - this was forced migration.
As more countries have joined the European Union many workers from poorer nations have exercised their right to travel to and work in other nations such as Britain.
When countries such as Poland, Hungary and the Czech Republic joined the EU in 2004, their citizens gained the right to move to the UK to live and work. This resulted in large numbers of immigrants coming to the UK in search of work as the UK economy was booming.
Between 2004 and 2006 the UK became the host country for 600,000 Eastern European migrants. Many found jobs, particularly in the construction and retailing trades, earning up to five times as much as they did in their home countries. Many send money home to their families.
As Eastern Europe developed and the UK economy struggled from 2008 onwards, many Eastern Europeans returned to their home countries. This means that their migration was temporary. Many Eastern European immigrants in the UK intend to return to their home country eventually.
Voluntary factors can be described as social or economic. Some examples of social factors are:
Economic factors include:
While migration can benefit countries, for example, by providing new trades, skills and a cheaper workforce, there are potential drawbacks to large scale migration.