While most legislation requires only a simple majority to pass in the Senate, there is a higher threshold for ending debate. By refusing to end debate, otherwise known as filibustering, a minority of senators can prevent legislative action they oppose. This concept of unlimited debate is unique to the Senate in the American political system. However, senators rarely used the filibuster until the late 19th century, eventually prompting the body to enact a reform allowing for cloture, a motion to end debate, in 1917. The cloture motion allowed the chamber to end a debate with a two-thirds majority vote. Over the following decades, senators found the two-thirds requirement to be an often unattainable bar, and they ultimately lowered it to 60 senators in 1975. Despite common misconceptions, the Senate does not require a “talking filibuster,” which forces a senator to continue talking to hold the floor and prevent the majority from passing a bill. Today, with increasing frequency, senators in the minority implement a “virtual” or “silent filibuster,” essentially allowing them to block legislation by simply threatening to exercise unlimited debate.