A filibuster is a parliamentary procedure used in the U.S. Senate to delay or block legislation by extending debate. Senators may speak for an extended period or employ other tactics to prevent a vote on a bill, often requiring a supermajority to end the filibuster, referred to as cloture. This tool can be used to protect minority interests or to negotiate amendments but can lead to legislative gridlock when parties are divided. The filibuster exemplifies the complex interplay of power in the Senate and serves as a significant mechanism in shaping legislative outcomes.