text: Alternatives to First-past-the-post voting include approval voting, two-round, proportional representation, and instant-runoff voting. With approval voting, voters are encouraged to vote for as many candidates as they approve of, so the winner is much more likely to be any one of the five marbles because people who prefer green will be able to vote for every one of the green marbles. With two-round elections, the field of candidates is thinned prior to the second round of voting. In most cases, the winner must receive a majority of the votes, which is more than half. If no candidate obtains a majority in the first round, then the two candidates with the most significant plurality run again for the second round of voting. Variants exist regarding these two points: the requirement for being elected at the first round is sometimes less than 50%, and the rules for participation in the runoff may vary.
  With single-round ranked voting, such as instant-runoff voting system as used in some elections in Australia and the United States, voters rank each candidate in order of preference (1,2,3,4 etc.). Votes are distributed to each candidate according to the first preferences. If no single candidate has 50% of the vote, then the candidate with the fewest votes is excluded and their votes are redistributed according to the voter's nominated order of preference. The process repeats itself until a candidate has 50% or more votes. The system is designed to produce the same result as an exhaustive ballot but using only a single round of voting.