A brain rain or human capital flight is a large emigration of individuals with technical skills or knowledge, normally due to conflict, lack of opportunity, political instability, or health risks. A brain drain is usually regarded as an economic cost, since emigrants usually take with them the fraction of value of their training sponsored by the government. It is a parallel of capital flight which refers to the same movement of financial capital. The term was coined by the Royal Society to describe the emigration of "scientists and technologists" to North America from post-war Europe. The converse phenomenon is brain gain, which occurs when there is a large-scale immigration of technically qualified persons.