Governments set rules for their citizens, protect them from harm and provide goods and services. Governments can be found at the national, state and local levels and may consist of either one person or many people with power to rule a particular territory. Governments make laws and regulations, raise money by taxing citizens and businesses, print money, enforce justice and provide a police force to prevent crime. Governments have a monopoly on the legal use of force.

Government is necessary to the existence of civilized societies. A variety of reasons for the evolution of governments have been proposed, including the evolutionary theory that states formed as a way to survive as families in a certain area. Another theory is that governments first evolved as a result of the need for groups to protect themselves from attack by other groups.

The main purpose of any government is to create the structure by which society can operate. Governments provide the parameters for everyday behavior for their citizens, protect them from outside interference and often provide for the general well-being of their people by providing jobs, social programs and medical care. The level of protection, welfare and economic security provided by governments varies considerably through time and place.

Different types of government exist because the needs of different societies vary. For example, if the society has a large percentage of poor people, it may be desirable to provide free public education, health care and housing as well as subsidize private business that can help these people. In a more prosperous society, it may be appropriate to encourage the development of large companies that can create high-paying jobs. In addition, a nation that wants to maintain a competitive advantage in the global marketplace must develop a system of research and development that can give it an edge over other countries.

People elect officials to govern them at the city council, city, township or county board of supervisors, state legislature and Congress. These people make law and draft budgets for the money they collect from taxes, a process that involves setting priorities for spending and deciding what programs should receive funding. At the state and federal level, funds are allotted to such things as school systems, maintenance of roads and bridges and wildlife management.

The separation of powers is an important principle in American government. James Madison argued that since it is impossible to create politicians who are angels who will never seek more power than they should have, the best way to keep them in check is by creating a system of checks and balances that requires each branch to perform its function independently of the other branches. This prevents a faction from controlling one branch of the government to such an extent that it is able to pass laws that would not be approved by the other branches of the government.

Governments regulate businesses by establishing rules that must be followed or businesses can face fines and lawsuits. Some of these rules are complex and difficult for small businesses to understand, making it difficult for them to comply.