This document discusses the interest group system in the United States. It defines interest groups and differentiates them from political parties. It outlines the different types of interest groups including economic, professional, citizens, and ideological groups. It also describes the strategies interest groups use to lobby and influence public policy, including acquiring access to officials, supplying information, grassroots lobbying, political donations, and electoral activities. Finally, it notes that while interest groups make important contributions to democracy, the system is biased in favor of economic groups.