As you probably know by now, the executive branch of the U.S. government is responsible for enforcing the nation's law. Laws do more than simply identify what people can't do, however. They also direct the work of government, dictating how it should operate on a daily basis. The federal government is an incredibly large organization, and its top executive, of course, is the president. Like executives in other organizations, the president needs help fulfilling the organization's mission.

The U.S. president is supported in enforcing the nation's laws by government agencies, permanent or semipermanent organizations that address specific issues and goals in the day-to-day administration of government. Organizations such as the Central Intelligence Agency (CIA), NASA, the Food and Drug Administration (FDA), and hundreds of others are responsible for regulating and coordinating all aspects of the daily lives of citizens, from national security to space exploration to regulation of prescription medication. The word agency, as it used to describe our government, can refer to whole departments or to small organizations that serve departments. Government agencies have a major impact on your life--whether you know it or not. Therefore, it's important to understand what they do and how they operate.