How-to-vote cards are leaflets that are handed out by party supporters during elections in Australia. Voting in the Australian lower house uses the preference voting system. Voters must rank every candidate on the ballot in order for their vote to count. There are often numerous candidates on the ballot, some with little public profile, so voters can find it hard to make up their minds on all of them. Parties produce how-to-vote cards to help voters. They contain details about the candidate or party as well as instruction how to cast a ranked vote in the order that the party wants the voter to follow. Voters are under no obligation to follow the cards. In South Australia, all how-to-vote cards are displayed on all polling booths. Sometimes "preference deals" are done between political parties so that they are favoured by each other's how-to-vote cards.