A caucus is a meeting of members or supporters of a political party or movement for discussion and decision-making on policies or candidates. It is used to select and nominate candidates for election and to shape the party's platform or agenda. Caucuses can be held at various levels of government, from local to national, and involve different groups, such as state delegates, party officials, and grassroots activists. The term caucus is commonly used in the United States, but similar processes exist in other countries with multi-party systems.