In a pure Democracy, all citizens vote on every decision made by the society. This was the system adopted by ancient Athens. Even then it was necessary to have someone to make the day-to-day decisions. Democracy is realistic only in small homogenous societies.
What we have in The United States and most of the Western world are Republics. While mimicking democracy, in republics, the populace elects people to represent their interests in governing the political unit. This is a practical evolution of pure democracy.
Aside from its impracticability in all but the smallest social units, democracy has many flaws. The prime problem is ‘rule by the mob’. The majority has absolute control of the society. Minorities have no power; it’s concentrated in the majority. “Power corrupts, and absolute power corrupts absolutely” Lord Acton. This is the major problem with democracies. When the majority has all the power they ‘lord’ over the minorities. Without power, the minorities are subject to the will of the mob. They have no rights, they can be enslaved, and their property seized, and even killed if that is the will of the majority. The first French republic is the perfect example of ‘rule by the mob’; first the Royalty was carted to the guillotine, then the petit bourgeois and eventually those who first seized power, Robespiere and his cronies. It took Napoleon and an eventual dictatorship to stop the “terrors.”
Republican democracies are by design slow to act. They have checks and balances to prevent hasty action in the heat of the moment. It takes debate to build a consensus among the representatives before action may be taken. While this is a slow process it has an advantage over totalitarian states. A Dictator may make a decision on the spur of the moment, and that decision may be disastrous for the state.
While technically we live in a Republic, most people think of America as a Democracy. As Winston Churchill so eloquently said it “Democracy is the worst form of government, save all others.”