The term regime refers in the political sphere to all that type of government formally established for a State, as well as the mode of organization of power that that State will have. In other words, the regime is the form or system by which a State exercises its government and through which it can also impart values, attitudes and ethical or thought structures.
Throughout the history of the human being we can find numerous types of political regimes that will vary especially in terms of access to power as well as the exercise of it. In this sense, regimes of the oligarchic, monarchical, aristocratic and plutocratic types are characteristic regimes from Antiquity to Modernity. In the case of Ancient Greece we can also find the democratic system, but more as an exception to the rule.
On the contrary, at present democratic regimes have been widely disseminated throughout the planet, although they nevertheless maintain special characteristics in each region. These can be basically presidential or parliamentary according to the power that exercises central functions in the government. At the same time, there are still monarchical regimes today (in some cases, parliamentary monarchies as in the case of Spain, Canada, Australia or England), as well as dictatorial and one-party regimes in which democratic practices are null.
It is common in the political history of each country to see alterations between different types of regimes that vary according to the time, to the most characteristic needs and concerns of each historical moment. In this sense, the United States is one of the few countries that has been able to maintain the same political regime based on representative and presidential democracy since its inception. Normally, the type of regime chosen by each country will be the one that accompanies the official name of that region, for example when we speak of the Bolivarian Republic of Venezuela, the Russian Federation, the United States of America or the Kingdom of Spain.