In some communities, speakers have developed forms of speech that involve inserting words from one language into utterances or sentences in another. Speakers may do this habitually, as a way of flagging their identity as a community, and sometimes as a way of maintaining a form of communication that is unique to them, and that is not understood by outsiders. These forms of speech as called "Mixed Languages". Sometimes mixed languages are used only as secret languages, in which case they only involve occasional insertion of words in order to prevent outsiders from understanding key concepts. In some cases, mixed languages are known to have become the first language of an entire community.