Also, Spanish is considered a lingua franca in the territories of the Spanish Empire and is one of the six official languages of the United Nations (other ones are Arabic, Chinese, English, French and Russian).
EXAMPLES
One of the earliest examples of lingua francas is Latin that was the lingua franca of European scholars until the 18th century.
Nowadays, there are still many examples of lingua francas. English, being of the most important languages in the world, is one of them. It is used by the international air traffic control as a common language. Moreover, English is used in other spheres of life by non-native English speakers whose native mother tongues are different in all over the world.