Migration involves people leaving their place of birth or residence to settle elsewhere. People migrate for reasons such as overcrowding in their home country, seeking better jobs or higher salaries abroad, or as a result of events like World War 2 in Europe. Immigrants to the UK face challenges including difficulties with language and cultural differences, racial prejudices, overcrowding exacerbated by higher birth rates among some groups, and complaints from residents about crime rates though the UK remains a diverse nation of mixed races and cultures.