This document outlines key concepts related to US campaign finance, including open and closed primaries, soft and hard money, and negative campaigning. It then discusses the history of campaign finance reform in the US, including the Federal Election Campaign Act of 1974 that set spending limits and disclosure rules in response to Watergate, but was weakened over time. The Bipartisan Campaign Reform Act of 2002 further reformed rules around soft money and issue ads, but new groups like 527s still spent millions in elections.