When a senator or a representative introduces a bill, he or she sends it to the clerk of his house, who gives it a number and title. This is the first reading, and the bill is referred to the proper committee. The committee may decide the bill is unwise or unnecessary and table it, thus killing it at once. Or it may decide the bill is worthwhile and hold hearings to listen to facts and opinions presented by experts and other interested persons. After members of the committee have debated the bill and perhaps offered amendments, a vote is taken; and if the vote is favorable, the bill is sent back to the floor of the house. The clerk reads the bill sentence by sentence to the house, and this is known as the second reading. Members may then debate the bill and offer amendments. In the House of Representatives, the time for debate is limited by a cloture rule, but there is no such restriction in the Senate for cloture, where 60 votes are required. This makes possible a filibuster, in which one or more opponents hold the floor to defeat the bill. The third reading is by title only, and the bill is put to a vote, which may be by voice or roll call, depending on the circumstances and parliamentary rules. A member who must be absent at the time of a vote may contract (or “pair”) with a member of the opposition to abstain, balancing each other out. The bill then goes to the other house of Congress, where it may be defeated, or passed with or without amendments. If the bill is defeated, it dies. If it is passed with amendments, a joint congressional committee must be appointed by both houses to iron out the differences. After its final passage by both houses, the bill is