A primary election (nominating primary) is an election in which voters in a jurisdiction select candidates for a subsequent election. In other words, primary elections are one means by which a political party nominates candidates for the following general election. "Primaries" are common in the United States, where their origins are traced to the progressive movement. There, primary elections are conducted by government on behalf of the parties. Elsewhere in the world, the nomination of candidates is usually the responsibility of the political party organizations themselves and does not involve the general public.

Besides primaries, other ways that parties may select candidates include caucuses, conventions, and nomination meetings. Historically, Canadian political parties chose their candidates in party meetings in each constituency. Canadian party leaders are elected at leadership conventions, although some parties have abandoned this practice in favour of one member, one vote systems.