A lingua franca is a language that people who speak different native languages use to communicate with each other. The term comes from Italian and literally means “Frankish language,” referring to a simplified form of Italian mixed with other languages that traders used around the Mediterranean Sea hundreds of years ago.

Today, English serves as the world's most common lingua franca. When a scientist from Japan, an engineer from Brazil, and a businesswoman from Egypt meet at an international conference, they'll probably speak English together, even though none of them grew up speaking it. At airports around the world, pilots and air traffic controllers use English as their lingua franca for safety reasons.

Throughout history, different languages have served this role. Latin was the lingua franca of educated Europeans for centuries. Traders along the Silk Road used Persian. In parts of East Africa, Swahili became a lingua franca because it allowed people from different groups to buy, sell, and exchange ideas.

A lingua franca doesn't replace anyone's native language. Instead, it acts like a bridge language that makes communication possible when people don't share the same mother tongue. Without lingua francas, international cooperation in science, business, and diplomacy would be nearly impossible.