The term “lingua franca” has two different meanings. In the first, it refers to a hybrid language integrating several European languages. This language was once widely spoken along the Mediterranean, used as a common mode of communication between people who would not have otherwise been able to speak to each other. In the second sense, a lingua franca is a language which is widely used as a basis of communication between people from different communities and cultures. This meaning is clearly related to the original meaning of the word.
Language is one of the greatest barriers to communication between people from different regions of the world. Generally, within a common geographical area, people may share a single common language although they speak different dialects. This ensures that people are able to trade and communicate about basic issues, often through a hybrid language which integrates several dialects. This language becomes known as a lingua franca, because it is considered a vehicular language, rather than a vernacular language.
A vernacular language or dialect is a language spoken by a relatively small and isolated group of people. For instance, Portuguese is a vernacular language spoken by people in Portugal. A vehicular language, on the other hand, is one which is used to communicate with people in other regions, who may speak unique vernacular languages on their own. In the Middle East, for example, Classical Arabic may be used as a vehicular language by people who speak different dialects.
French and English have both been known as common languages at various points in history. French, for example, was once the lingua franca of diplomacy, with diplomats communicating in French at formal meetings and conferences. English is often treated as a lingua franca of the technology sector, allowing people in different nations to communicate about various technological issues. In Africa, languages like Swahili are sometimes used in this way by people from different tribes and regions.
Many pidgin languages are also treated like a form of lingua franca. Pidgin languages have commonly developed when Europeans have contact with regional tribes, for example; they are designed to facilitate communication between these radically different cultures. Pidgin is usually simple and clear, and it may not be ideal for complex concepts or ideas, but it's perfectly suitable for trade and basic negotiations.