Every law starts as an idea. That idea can come from anyone — a regular citizen, an advocacy group, a business, the President, or a member of Congress themselves. People contact their representatives all the time with suggestions for new laws or changes to existing ones.

Once a member of Congress decides to champion the idea, they draft it into a formal document called a "bill." In the House of Representatives, the member drops the bill into a special box called the "hopper." In the Senate, they formally introduce it on the floor. The member who introduces the bill is called its "sponsor," and other members who support it can sign on as "cosponsors."

Having many cosponsors early on signals broad support and can improve a bill's chances of moving forward. Some bills are introduced with bipartisan cosponsors from both parties, which often signals a stronger chance of passage.