The public affects the workings of government in many ways. It can affect the government both directly and less directly.
The most direct way in which the public can influence the government is through lobbying. Interest groups made up of members of the public hire people to go and express their opinions on various issues to Congress and to other parts of the government. This is the most direct way for the public to have input on specific issues.
A major indirect way for the public to influence the government is through voting. The public affects the government by choosing its members. This is a less direct way of affecting the government because it does not tell the government how to act on any particular issue.
These are the two most important ways in which the public affects the government.