A filibuster is a political tactic used in the United States Senate to delay or block legislation. It allows a senator or a group of senators to speak for an extended period, often for hours or even days, to prevent a vote on a bill. This tactic can be used to draw attention to specific issues or to negotiate changes to proposed legislation. To end a filibuster, the Senate can invoke cloture, which requires a supermajority of 60 votes. If successful, cloture limits further debate and allows the Senate to proceed to a vote. Filibusters are a controversial aspect of the legislative process, as they can lead to gridlock in government.