In political science, voter turnout is the participation rate (often defined as those who cast a ballot) of a given election. This is typically either the percentage of registered voters, eligible voters, or all voting-age people. According to Stanford University political scientists Adam Bonica and Michael McFaul, there is a consensus among political scientists that "democracies perform better when more people vote."

Institutional factors drive the vast majority of differences in turnout rates. For example, simpler parliamentary democracies where voters get shorter ballots, fewer elections, and a multi-party system that makes accountability easier see much higher turnout than the systems of the United States, Japan, and Switzerland.