First past the post

First past the post or plurality voting is the simplest kind of voting system. Each voter votes for one candidate, and whichever candidate gets the most votes is the winner.

Though OK for two-candidate races, it is bad for more than two, because it encourages voters to vote for the lesser of the two major evils in order to keep the greater one from winning. Fear of wasting one's vote causes convergence on two-party systems, an effect called Duverger's law after Maurice Duverger, the sociologist who noticed and described that effect.

Most alternatives to first-past-the-post are more friendly to multiple candidates and parties. The simplest of them is runoff elections. If no candidate wins a majority, then the two top candidates have another election. The President of France is elected in that fashion. Instant Run-Off Voting and proportional representation do even better at being multiplicity-friendly.

FPTP continues to be used in two of the oldest present-day democracies, the United States and the United Kingdom, even though many others have abandoned it for various approximations of proportional representation.