Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is an official language of Papua New Guinea. It is a simplified version of Motu, of the Austronesian language family. Although it is strictly neither a pidgin nor a creole, it possesses some features of both language types. Phonological and grammatical differences mean that Hiri Motu speakers cannot understand Motu. Similarly, Motu speakers who do not also learn Hiri Motu have similar difficulties, though the languages are lexically very similar, and retain a common Austronesian syntactical basis. Even in the areas where it was once well established as a lingua franca, the use of Hiri Motu has been declining in favour of Tok Pisin and English for many years.