Democracy can broadly be defined as a system in which the people govern themselves. Democracy can take a variety of different forms, including direct, parliamentary and presidential democracy. Parliamentary democracy is a distinct type of democracy in which citizens vote for representatives, and a majority of those representatives form a government or executive branch. Today, parliamentary democracy is the most common form of democracy among nations.

Direct Versus Representative

Direct democracy is one form of government that can be clearly distinguished from parliamentarism. In direct democracy citizens rule themselves directly by holding political office and exercising political rule rather than relying on representatives. Examples of direct democracy include ancient Athens, in which all adult male citizens had the right to participate in making laws and the 1871 Paris Commune, in which workers' councils were formed through the direct participation of Commune members. In contrast, parliamentary democracy is a representative democracy. Citizens vote for professional politicians to represent them in parliament, rather than directly ruling themselves.

Separation of Powers

Presidentialism is another type of democracy. Like parliamentary democracy, presidentialism is a form of representative, rather than direct, government. Unlike parliamentary democracy, in presidentialism, executive power is separated from legislative power, and the executive is usually elected separately from the legislature. For example, in the United States, the constitution distinguishes between the powers of Congress and those of the president, and each are elected separately. In contrast, in parliamentary democracies such as the United Kingdom, the executive of the government is chosen from the majority party in parliament or by a coalition of parties. There are no separate elections for the executive.

Passing Legislation

It is often easier to pass legislation in parliamentary democracies than in presidential democracies because of the absence of a distinct executive branch. Presidential democracies like the United States often feature checks and balances, which means that the powers of different branches overlap. For instance, United States presidents do not have the power to pass legislation but they do have the power to veto legislation passed by Congress, which can only be overridden by a two-thirds majority of Congress. In contrast, in most parliamentary democracies the executive has a much easier time passing legislation, since the executive generally enjoys a majority or majority coalition in parliament.

Process and Deliberation

While some political scientists such as Juan Linz in the book "The Failure of Presidential Democracy," argue that the relative ease of passing legislation in parliamentary democracy makes it preferable over presidential systems, scholars such as constitutional law scholar and Yale professor Bruce Ackerman argues in his book "We the People," that presidential systems can have more informed political deliberation than parliamentary ones. Whereas passing laws is relatively straightforward in parliamentary democracies, decision makers in presidential democracies must engage in more persuasion, public debate and deliberation to enact legislation. This potentially makes a presidential democracy slower and more unwieldy, but it does have the benefit of sustaining more public deliberation and debate than parliamentary democracy requires.