Lingua Franca: A language used among speakers of different languages for the purposes of trade and commerce. The lingua franca in Australia is English. "English Explorer" states, "Why English has become the world's lingua franca is due to the fact that is the common language or mode of communication that enables people to understand one another regardless of their cultural and ethnical backgrounds. It makes communication a lot easier and understanding one another has become efficient" (Why The English Language Became The World's Lingua Franca).
Pidgin: When people speaking two or more languages are in contact and they combine parts of their languages in a simplified structure and vocabulary. A pidgin language in Australia is Australian Kriol. Wikipedia states, "Australian Kriol is an English-based creole language that developed from a pidgin used initially in the region of Sydney and Newcastle in New South Wales, Australia, in the early days of European colonisation. Later, it was spoken by groups further west and north" (Australian Kriol).
Creole: A pidgin language with a more complex structure and vocabulary that has become the native language of a group of people. An example of this in Australia is Kriol. Wikivoyage states, "Kriol is an English-based creole language spoken in the Top End and Kimberley regions of Northern Australia. It is spoken mainly in remote communities by Australian Aboriginals. It is distinct from Torres Strait Creole and Aboriginal English" (Australian Kriol Phrasebook).