Speakers who routinely speak more than one language may use their languages in ways slightly different from a single language speaker, or a monolingual.

The numbers may generally reflect a relatively broad definition of language speakers, leading to somewhat higher numbers than other contemporary estimates.

Many are close enough in terms of vocabulary and grammar to permit communication between some other language speakers.

Issues caused by the linguistic variation range from total communication breakdowns involving foreign language speakers to subtle difficulties involving bilingual and bidialectal speakers.

However, the regions are not equal in terms of language speakers.