Government is the institution that makes and enforces rules to keep society peaceful and orderly. It also provides security and services to its citizens that individuals or small groups of people are not able to provide for themselves. Government also helps its citizens to fulfill their moral obligations to care for one another. Government cannot do this well without the cooperation of its citizens. They need to accept its rules and laws as legitimate, even if they vehemently disagree with them, and refrain from using the power of the state for their own selfish ends.

The United States Constitution lays out the framework for how our federal, state, and local governments should work. It divides the nation into three branches: legislative, executive, and judicial. The founding fathers wrote the Constitution to limit the powers of government and ensure that it works effectively.

It is the responsibility of governments to preserve themselves against external threats as well as internal rebellion or discord. To accomplish this goal, they must maintain armed forces, carry out intelligence activities, and impose restrictions on the entry of aliens who may be spies or terrorists. They must prevent the sale of weapons or other materials that could aid a potential enemy and imprison or expel such agents as they discover them. Finally, they must be prepared to wage war if the threat becomes serious.

Another important role of government is to promote life-affirming patterns of behavior and discourage destructive ones. Its purpose is to encourage good and protect the weak from those who would exploit them. Governments do this by providing education and social services, building roads, hospitals, and schools, and ensuring that citizens are protected against crime and natural disasters.

To help its citizens, a government must enact and enforce laws that prohibit theft, murder, and assault. It also must provide health and welfare services, such as food stamps and unemployment insurance. Finally, it must provide for the safety of its citizens and their property by maintaining police forces, fire departments, and military defenses.

A government needs money to do all of these things. To get it, it must collect taxes. Governments often spend more than they receive in revenue, and when that happens they must borrow money. To do that, they sell bonds to the public. A bond is a kind of IOU, and the buyer pays up front in exchange for an IOU that will be redeemed at some point in the future for the original amount plus interest.

In a democracy, citizens have many ways to influence the policies that their government adopts. For example, if they disagree with a law that Congress passes, they can try to persuade the president to veto it. If Congress votes to override a presidential veto, it must do so by a two-thirds majority. The Supreme Court and other federal courts (judicial branch) can declare laws or executive actions unconstitutional, in a process known as judicial review.