Governments set the rules for everyday behavior, protect citizens from outside interference and often provide benefits like healthcare, education and even food. They also manage common goods that are in limited supply, such as public schools, mail carriers and wildlife.

People first developed governments because they recognized that being part of a group made it easier to protect themselves against attacks by other groups. The leaders of these groups (later called nations) agreed to limit the power of one person over another within the group and to protect everyone’s property.

Today’s governments are more concerned with ensuring that everyone has an opportunity to succeed. They do this by encouraging growth and development, limiting the number of people who live in poverty and providing for those with special needs. They have also been responsible for protecting the environment, regulating the use of certain chemicals and materials and ensuring that people are not poisoned by lead in their drinking water or exposed to dangerous fumes from cars.

There are three main levels of government: national, state and local. Each level has a different role. State and local governments manage things such as holding elections, maintaining roads, providing health care and social services and managing schools. Federal government takes care of things like foreign policy, the minting of money and enforcing federal laws. In the United States, all of this is overseen by a system of checks and balances, wherein the president has some executive powers but Congress can stop him by appropriating funds for military actions or passing a law that overturns his proclamations.

The founding fathers created this system of separation of powers based on their experience, and they hoped that it would prevent too many people from taking control of the nation. They feared that too much power in the hands of too few people could lead to corruption and ruin. They designed the system to ensure that no one branch of government had too much power and that each branch complemented the others, as illustrated in our infographic below.

The branches of government are not equal, however, and no branch of government has complete control over all other branches. For example, in the United States, Congress (legislative branch) makes the laws and passes them on to the president for approval or veto, while the Supreme Court and the courts of appeals interpret those laws. In addition, the Senate in the legislative branch confirms the president’s nominations for judicial positions, while Congress can impeach a Supreme Court justice or court of appeals judge and remove them from office.