The single transferable vote (STV) system is designed to ensure that the winning candidate has the support of a majority of voters by allowing voters to rank candidates in order of preference. If no candidate receives a majority of first-preference votes, the candidate with the fewest votes is eliminated and their votes are transferred to the next-highest-ranked candidate on each voter's ballot. This process continues until a candidate receives a majority of votes.

The main advantage of the proportional representation voting system is that it ensures that all parties receive a share of seats in the legislature that is proportional to their share of the vote. This makes it more likely that the legislature will reflect the diversity of views in the electorate and that all parties will have a say in the decision-making process.

The first-past-the-post voting system is the most commonly used voting system in the United States. In this system, the candidate who receives the most votes in a given election wins, even if they do not receive a majority of the votes. This system is often criticized for leading to two-party dominance and for making it difficult for third parties to win elections.

The main disadvantage of the first-past-the-post voting system is that it can lead to a situation where the winning candidate does not have the support of a majority of voters. This can happen when there are multiple candidates running for office and the vote is split between them. In such cases, the candidate who wins may only have the support of a plurality of voters, which means that they received more votes than any other candidate, but not a majority of the votes.

Ranked-choice voting is designed to make it easier for third parties to win elections by allowing voters to rank candidates in order of preference. If no candidate receives a majority of first-preference votes, the candidate with the fewest votes is eliminated and their votes are transferred to the next-highest-ranked candidate on each voter's ballot. This process continues until a candidate receives a majority of votes. Ranked-choice voting is used in some cities and states in the United States, as well as in some other countries.

The main advantage of the ranked-choice voting system is that it makes it easier for third parties to win elections. This is because ranked-choice voting allows voters to rank candidates in order of preference. If no candidate receives a majority of first-preference votes, the candidate with the fewest votes is eliminated and their votes are transferred to the next-highest-ranked candidate on each voter's ballot. This process continues until a candidate receives a majority of votes. This makes it more likely that a third party candidate will be able to win an election, even if they do not receive the most first-preference votes.

The first-past-the-post voting system is used in the United Kingdom. In this system, the candidate who receives the most votes in a given election wins, even if they do not receive a majority of the votes. This system is often criticized for leading to two-party dominance and for making it difficult for third parties to win elections.

The main disadvantage of the proportional representation voting system is that it can lead to a situation where no party has a majority of seats in the legislature. This can make it difficult to form a stable government and can lead to political instability. Additionally, proportional representation can make it more difficult for voters to understand how their votes will be counted, as the allocation of seats in the legislature is based on the overall share of votes received by each party, rather than the number of votes received in each individual constituency.

The proportional representation voting system is used in Germany. In this system, the seats in the legislature are allocated to parties based on the share of votes they receive in the election. This system ensures that all parties have a voice in the decision-making process and that the legislature reflects the diversity of views in the electorate.

The main advantage of the single transferable vote (STV) voting system is that it ensures that the winning candidate has the support of a majority of voters. This is because STV allows voters to rank candidates in order of preference. If no candidate receives a majority of first-preference votes, the candidate with the fewest votes is eliminated and their votes are transferred to the next-highest-ranked candidate on each voter's ballot. This process continues until a candidate receives a majority of votes.

New Zealand uses a mixed-member proportional (MMP) voting system. This system combines elements of both the first-past-the-post and proportional representation systems. In MMP, voters cast two votes: one for a local candidate in their electorate and one for a party list. The seats in the legislature are then allocated based on the number of votes received by each party, with some seats being reserved for local candidates and others being allocated to party lists.

The main disadvantage of the mixed-member proportional voting system is that it can lead to a situation where no party has a majority of seats in the legislature. This can make it difficult to form a stable government and can lead to political instability. Additionally, MMP can make it more difficult for voters to understand how their votes will be counted, as the allocation of seats in the legislature is based on a combination of the votes received by local candidates and party lists.

Australia uses a compulsory preferential voting system. In this system, voters are required to rank candidates in order of preference. The candidate who receives the most first-preference votes wins the election. If no candidate receives a majority of first-preference votes, the candidate with the fewest votes is eliminated and their votes are transferred to the next-highest-ranked candidate on each voter's ballot. This process continues until a candidate receives a majority of votes.

The main advantage of the compulsory preferential voting system is that it ensures that the winning candidate has the support of a majority of voters. This is because voters are required to rank candidates in order of preference. If no candidate receives a majority of first-preference votes, the candidate with the fewest votes is eliminated and their votes are transferred to the next-highest-ranked candidate on each voter's ballot. This process continues until a candidate receives a majority of votes.

Canada uses a first-past-the-post voting system. In this system, the candidate who receives the most votes in a given election wins, even if they do not receive a majority of the votes. This system is often criticized for leading to two-party dominance and for making it difficult for third parties to win elections.