Lingua franca（混合语；族际通用语）：

It is the general term for a language that serves as a medium of communication among groups of people for diverse linguistic backgrounds.It can be an
internationally used language like English，or the mother tongue of one of the groups.It can also be a language that has no native speakers but has a simplified sentence
structure and vocabulary，and is often a mixture of two or more languages.For this reason，a lingua franca must bean agreed-upon common tongue used by people thrown in social contact for various purposes.