In a democracy such as ours, which has a representative form of governance, whereby we vote for people who will make decisions on various matter for us, this is an advantage and a disadvantage. When we elect people to make these various decisions, it is not at all clear whether they are elected because we want them to exercise their own intelligence, logic, experience, and ethical values or we want them to represent our opinions. There is no law governing this in our democracy, and it is indeed a two-edged sword. Should our representatives do the former or the latter? There are advantages and disadvantages inherent in each. Few of us as individuals are able to be fully informed on every issue that comes before a legislator, an executive, or a judge. It can be a good thing for people who are elected because they are or can be fully informed to make such decisions for us. But it can have consequences that we do not think of as truly "democratic" when an elected official makes a decision that does not represent the will of the majority, even when the decision made might be reasonably construed to be the best decision, for all, or in the long run. We would all want to give some very careful thought to the notion that all decisions by elected or appointed individuals should be made through poll-taking. If that were the case, we would have a sort of direct democracy, but what would be the point of having elected or appointed officials at all? And that brings us to the next way some issues are decided.
Democracy also, though, can include the referendum, which is a decision that people vote upon directly, for example, whether or not to allow medical or recreational marijuana use in a particular state or whether or not to allow same-sex marriage. This is the purest form of democracy, truly representing the will of the majority, but this has the disadvantage of a majority making a bad decision, since, again, very few of us are as well-informed as we could be or should be to weigh in on these matter. Furthermore, these are state referenda, and the American Constitution can trump any of these, for very good reason.
We have been speaking of democracy in a kind of a vacuum, ignoring what might be the most important aspect of American democracy, which is that it is a constitutional democracy, which places limits on the powers of those whom we elect or appoint, limits that at least theoretically protect all of us as we cede authority to those we elect or represent. One of the difficulties in developing democracies is that without a carefully crafted constitution, all of the disadvantages of democracy emerge, with few of the advantages.