The 21st century has brought with it a fourth pillar of state. When the United States was founded, it was based on three pillars: executive power, an elected legislature, and an independent judiciary. The fourth pillar is a free media. As the information age has powered ahead, the fourth pillar has become more and more important. These powers are maintained by a system of checks and balances so that no one pillar may overtake the others entirely. Exactly what the four pillars are is up for interpretation based on what an individual believes to have the most value in a democratic society. Some people would add public education and transparency as pillars as well.
In a constitutional democracy like the United States or Great Britain, the executive branch of government is represented by a presidential or parliamentary system of government. In the parliamentary system, the national leader is drawn from the parliament and is called the prime minister. The parliament is formed by the majority party and those willing to work with it. The prime minister and the parliament function more closely together than the president and legislature in the presidential system.
In the presidential system, the president is elected in a separate election from the legislature. The president and the legislature may have different parties drawing on their own political power bases separate from one another.
The legislature or parliament serves to introduce, debate and pass laws. Legislators are involved in national budgets, approval of executive appointees to Federal positions, and they check the actions of government agencies through investigation. These legislators are charged with representing the area that they are from as well as the greater good of the whole nation.
An independent judiciary is necessary for the court system to function. The ability to function without fear of reproach is key to unbiased decisions based solely on the law in question. This independence ensures equal protection under the law for all citizens. Judges may only be removed from the bench through impeachment. The tenure associated with their positions allows them to operate without fear of losing their jobs based on making an unpopular decision.
A free media is imperative for a democratic state to function. The media serves as a watchdog for its people providing information they may not otherwise have access to or seek out themselves. A free media allows individual citizens to question those in power and use that information to make decisions about their future.