A primary election is conducted so that voters can select candidates for a subsequent election (this is called the nominating primary). Primary elections allow each political party to determine its nominee for the upcoming general election.
Primary elections are classified by various categories:
- Open: Voters may vote in the primary election of the party of their choice, regardless of their own party affiliation. Voters cannot, however, vote in more than one party's primary; they must choose one and only one.
- Closed: Voters must declare their party affiliation in advance of the primary election, and can only vote in that party's primary. To participate in a party's closed primary election, voters must identify their party affiliation when they register to vote.
- Semi-closed: Voting is restricted to voters who have already declared their party affiliation in advance, and to new and/or Independent (unaffiliated voters) who choose which primary to vote in on Election Day. To participate in a party's semi-closed primary election, voters must identify their party affiliation when they register to vote.
- Semi-open: Voters can choose which party's primary to vote in on Election Day, regardless of their party affiliation, but must make a public declaration of that choice in front of election judges.