It must pass various requirements: after being created, it must be introduced to the U.S. House of Representatives, then it has got to the committee members who are experts that will review it (the title, clauses, amendments etc.). Once the committee approved the piece of legislation it is sent back to the House of Representatives to be voted on; it is when they will discuss the bill and explain why they agree or disagree with it, then vote on it. Only after these steps the bill can proceed to the Senate, who will do basically the same process as before.
