Sometimes in situations of bilingualism, speakers change the way they speak because of the influence of other speakers' way of speaking. If this situation persists over a long period of time, two or more languages can become more and more similar. This can affect the vocabulary, the pronunciation, or, quite often, the sentence structure and the grammar of the languages concerned. We describe this process as a "Convergence" of languages. There are many regions in the world in which multilingualism has had this effect over a long period of time. A well-studied example of language convergence is the one in the Balkans where different languages (such as Greek, Albanian, Romania, Bulgarian) all share certain features of grammar.