Can doctors work in different countries other than their own country?

Doctors wishing to practice outside of their own country of origin generally belong to organizations such as the World Health Organization, United Nations, Doctors Without Borders, and so forth. A doctor wishing to work outside a country other than that in which they trained would have to satisfy the new country that their qualifications were equal. There is freedom of movement throughout the EU and there are many doctors in the UK from other English speaking countries. Many British doctors also go to other English speaking countries including the US.