From the Summary: "The filibuster is widely viewed as one of the Senate's most characteristic procedural features. Filibustering includes any use of dilatory or obstructive tactics to block a measure by preventing it from coming to a vote. The possibility of filibusters exists because Senate rules place few limits on Senators' rights and opportunities in the legislative process. […] This report concentrates on the operation of cloture under the general provisions of Senate Rule XXII, paragraph 2, though it also identifies key modifications to its application in recent years. This report will be updated as events warrant."
CRS Report for Congress, RL30360
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html