Public Opinion is just what it sounds like. It is what the public's reaction and/or feelings are on a given issue. The opinions of the public however can differ under certain circumstances.

First, consider the stability of public opinion. During FDR's presidency, for example, the public wanted government involvement to help them out of the depression. Now, federal involvement is not sought after as much. As time progresses, so do the opinions of the public. They change according to the current political climate, etc.

Oftentimes, the results of surveys are skewed and, therefore, public opinion is misrepresented. This is partly due to the public's ignorance. We want to seem like we're informed. However, most of the general public is not; they simply act like they are.

Also, they way in which the question on a given survey is posed can yield different results. Asking one-sided questions vs. two-sided questions acquires significantly diverse results.