What is the process in which a bill becomes law in congress?

The bill is introduced in either the House or the Senate by one or more members. It is referred to a committee for review. If the committee votes to pass it forward, it goes to the entire House or Senate where it can be amended (changed) and then voted on. If it passes then it must wait until the other house of Congress (the one that didn't introduce it originally) goes through the same process for a similar bill.

When both versions of the bill have been approved by both Houses, they form a conference committee made up of members from both the House of Representatives and the Senate to try and make the bill into a single version that all can accept. If they are successful, the new single bill goes to both Houses to be voted on. If it passes both Houses, it goes to the President.

The President can either sign the bill into law, or veto it. If he vetoes a bill it goes back to Congress. If at least 2/3 of both Houses re-pass it, it becomes law without the President's signature.