Filibuster refers to a tactic that is used in the Senate in order to block a bill being considered by preventing it from being voted on passage. The only way to defeat a filibuster os by gaining passage of a cloture motion. This requires a three-fifths majority vote of the Senators present. The reason why filibusters do not take place in the House of Representatives is because the House has rules that limit the time spent on debates. On the other hand, the Senate places few limits on the rights of senators.
A recent filibuster occurred in 2016 when senator Chris Murphy gave an emotional debate on the subject of gun measures that lasted 15 hours. The result of this was that Murphy was able to secure votes on gun measures from both Democrats and Republicans.