What is a filibuster and what house can it occur in?

A filibuster in the United States Senate usually refers to any dilatory or obstructive tactics used to prevent a measure from being brought to a vote. The most common form of filibuster occurs when a senator attempts to delay or entirely prevent a vote on a bill by extending the debate on the measure, but other dilatory tactics exist. The rules permit a senator, or a series of senators, to speak for as long as they wish and on any topic they choose, unless "three-fifths of the Senators duly chosen and sworn" (usually 60 out of 100 senators) brings debate to a close by invoking cloture under Senate Rule XXII.