I’m assuming you’re mentioning Congress. Both the Senate and House consist of committees that do different things. So instead of the entire body of people, it’s a small group. Usually people who obtain a significant amount of knowledge when it comes to the particular subject. Depending on what policy, law, etc is being put in place, depends on the committee it goes to. Once voted, it goes to the main floor for the final vote. There’s more steps to it but it’s not needed for what you’re asking. Good luck.