In Western liberal democracies, including Australia, political parties are the intermediate structure between society and government. Modern democracy is party democracy. Representative government is party government. Elections are essentially party contests.
Legislatures are party chambers.
Politics is party politics. Political parties are central to all levels of political activity, debate and decision-making. Political parties serve a number of purposes. They enable diverse interests to be aggregated, articulated and represented. They are the major actors in formulating policies and in communicating those policies to the electorate.