A filibuster in the United States Senate ends by a cloture. A cloture is when two-thirds of the Senate vote to break the filibuster. However, it only limits the time; a filibuster can continue up to 30 hours.
Filibusters were originally created so that all the voices of the Senate were heard, even those not in the majority. Even after the rules allowed for filibusters in 1806, the Senate did not have one until 1837. Modern filibusters are used to keep laws from being passed, and sometimes filibusters are used to keep others from debating.
Cloture is effective at limiting filibusters. However, because it requires a two-thirds vote, clotures are often difficult to complete.