How does a bill become a law in the United States?

Somewhere in America, an idea is having a very big day. Maybe it's "bridges should be safer" or "school lunches deserve more vegetables." Right now it's just a hope written on paper. But this little paper has a dream: it wants to grow up and become a law. Buckle up — it's a long, twisty road, and a surprising number of people get to say no.
First, the idea needs a sponsor — a member of Congress who likes it enough to put their name on it. The moment they officially drop it in the hopper, our paper gets a fancy new title: a "bill." Congress, by the way, has two halves: the House of Representatives and the Senate. A bill can start in either one. Let's say ours begins in the House.
