State police (or State troopers) are a type of sub-national territorial police force, particularly in Australia and the United States. Some other countries have analogous police forces, such as the provincial police in some Canadian provinces, while in other places, the same responsibilities are held by national police forces.
Each state of Australia has its own state police force. Municipalities do not have police forces and it is left to the state forces to police the geographic areas within their respective states. Australia does have a national police force, the Australian Federal Police, whose role is to enforce the laws of the Commonwealth, both criminal law and civil law, as well as to protect the interests of the Commonwealth, both domestically and internationally. The AFP does, however, provide 'state' policing for the Australian Capital Territory, Jervis Bay Territory, and Australia's other external territories such as Norfolk Island.
Prior to the Federation of Australia, each Colony within Australia had numerous police forces, but these were largely amalgamated well before Federation.