voting.wiki

Overview of Voting Systems

A voting system is the set of rules that determine how elections and referendums are conducted and their results determined. Electoral systems are the detailed constitutional arrangements and voting systems that convert the vote into a political decision. The choice of electoral system profoundly impacts the nature of political representation and the distribution of power.

There are dozens of voting systems in use around the world, each with distinct properties related to fairness, simplicity, and strategic resistance. This encyclopedia provides comprehensive coverage of the most important systems, their mathematical properties, and real-world applications.

Plurality Voting

Also known as first-past-the-post (FPTP), plurality voting is the simplest form of voting system. Each voter selects one candidate, and the candidate with the most votes wins. It is the most widely used system for single-winner elections worldwide, employed in the United States, United Kingdom, Canada, and India for legislative elections.

How It Works

Under plurality voting, each voter casts a single vote for their preferred candidate. The candidate who receives the most votes is declared the winner, regardless of whether they achieve a majority (more than 50%) of the total votes cast.

Advantages and Disadvantages

Ranked Choice Voting

Ranked choice voting (RCV), also known as instant-runoff voting (IRV), 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 redistributed according to second preferences. This process continues until a candidate achieves a majority.

The Counting Process

RCV is used in Australia for federal elections, in Ireland for presidential elections, and in several U.S. cities and states including Maine and Alaska. It is designed to avoid the spoiler effect and ensure the winner has broad support.

Approval Voting

In approval voting, each voter may select ("approve") any number of candidates. The candidate approved by the most voters wins. This system is praised for its simplicity and tendency to elect broadly acceptable candidates rather than polarizing ones.

Properties

Approval voting satisfies the monotonicity criterion: voting for a candidate never hurts them. It is immune to the spoiler effect in practice, as voters can always vote for their favorite without risking helping their least-preferred candidate win.

Voting Method Simulator

Enter voter preferences below and see how different voting systems produce different outcomes from the same set of ballots. Drag to reorder preferences for each voter group.

System Comparison Matrix

The following table compares key mathematical and practical properties across major voting systems. A checkmark indicates the system satisfies the property; a cross indicates it does not.

Country Directory

Electoral systems used for national legislative elections around the world. Use the filter to search by country name or system type.

Showing 14 of 14 countries