The Constitution specifically gives to Congress its most important power - the authority to make laws. This law-making power is shared by both houses. No bill (proposed law) can become law without the consent of both houses.
Suggestions for bills - be they about education, violence against women, trade with China, gun control or foreign aid - can come from the president, executive agencies, committee staffs, interest groups, or even private individuals. Only Members of the House or Senate, however, can submit a bill to Congress. Every law passed by Congress starts out as a bill, but most bills never become laws. Of the approximately 10,000 or so bills introduced during any session of Congress, fewer than 5 percent are made into law.