Closed primaries are a type of electoral process used by some political parties to select their candidates for the general election. In a closed primary, only registered party members can vote to choose their party's nominee. This means that individuals who are not affiliated with that party cannot participate in the voting process. The purpose of closed primaries is to ensure that only dedicated party members influence the selection of candidates. This system can help maintain party unity and prevent members of opposing parties from interfering in the nomination process. Closed primaries are common in states like California and New York.